Here is why you are wrong:
1) Scams. The Internet is full of scams. Most of them existed before bitcoin and will continue to exist if bitcoin went away. Bitcoin puts more risk to the buyer while PayPal transfers the risk (of charge backs) to the seller. sellers love bitcoins while buyers love PayPal. One is not better than the other. They are just different. Right now bitcoin is used mainly for transactions with individuals and small companies. Imagine if amazon.com accepted bitcoin. Would you hesitate to buy merchandise from them with bitcoin? I'm guessing you wouldn't have an issue with because they are large, trusted company. Bitcoin is like cash and cash has existed for a long time without reversible transactions.
In the future there will be online wallets that insured by the companies holding them so that your coins are safe even it their site is hacked. There is nothing to prevent this from happening once banks get in on the bitcoin game. Only libertarians -- the kind that keeps gold bars in a safe and cash under their mattress will bother keeping their savings in a local wallet,
How would it be possible to insure that the wallet will remain safe? Assuming that Amazon uses bitcoins, and some random guy found the private key of the wallet, and send all the bitcoins to a mixing service. How would you retrieve the coins? How would you revert an irreversible transactions? How do you track an untrackable move?
2) Bitcoin is inconvenient. Yes, bitcoin isn't convenient to use now but there is nothing that says it must always be this way. New software will be developed that will make bitcoin easier to use. New exchanges will be started that will make it easier to buy and sell bitcoins (I personally think that coinbase is pretty darn simple). And in the future no one will ever be downloading the whole blockchain. People will use online wallets, or they will use local wallets that don't require the whole blockchain. Bitcoin ATMs will be out there and there will be plenty of easy to use mobile bitcoin apps and wallets. If you can use online banking, you'll be able to use bitcoin. Bitcoin is still new there ans we have a ways to go but there is no reason we can't get there.
I think that it is not a big deal, with safety is the main problem. You can see in the newbie section people complaining about comprised online wallet every day, even with double authentification ON.
3) Fees are too high. This is not true at all. Fees are very low right now. In fact, you can still send bitcoins for free and have your transaction accepted into the blockchain. Worst case scenario, you have to add 5 or 10 cents to the transaction.
Fees do not need to go up once the block reward goes away!! Why not? Well, the fees can stay low because by then we expect the NUMBER of transactions per block to greatly increase as bitcoin becomes more widespread. Fees can still be 5 cents per transaction. The difference is we will have 1000 times more transactions.
Furthermore, credit cards are NOT free. Credit card companies charge merchants 2-3% to process transactions. Who ends up paying that? Well, you do in the form of higher prices. Merchants would love to charge you less if you use cash (and many gas stations do) but in general the credit card industry imposes strict rules to prevent merchants from doing that if they want to be able to accept credit cards at all.
Exchanges currently are a pain to use and can be expensive. But as Bitcoin gains acceptance and there are more exchanges, increased competition will bring lower fees and easier to use exchanges. In the future, exchanging fiat for bitcoin will be done for such a small fee it will be essentially free.
Current fees: 0,005 btc = 67,25 USD cents.
If you are buying a car it's fine. But if you are buying a 1 USD item, or moving money from wallet to wallet, it can increase quite a lot: almost 7 USD for 10 transactions, that you can do within 12 hours.
The numbers of transactions can go up, or down, and the fees as well. In the future, it might even not be possible to send btc without the fees.
Why would I care if the seller pays fees to VISA? If I am a customer and I don't pay anything, I don't pay more if I pay with a credit card, or by cash, I don't really care... You say that some merchants are selling cheaper if you pay by cash? I have never seen any of these.
Do you think that the blockchain will accept more transactions by blocks?
I have been waiting for 3 days for my last transaction to proceed (no fees). It took 45 minutes to get one confirmation with a 67 cents fee. I am not sure, but it seems that it is taking longer and longer to confirm. Before, transactions with fees were instant, and without took 12 hours max.
4) Confirmations are too slow. No, they are virtually instantaneous. There is no reason for most ,enchants to even wait for a block confirmation. Double spending is almost impossible to perform in practice and I've yet to hear of anyone successfully double spending in the real world ever. And the risk can be reduced if the merchant uses a payment processor that watches the network for double spend attempts. Already merchants such as Foodler will credit your bitcoin deposit immediately without waiting for confirmation. The only time a merchant might want to wait for confirmation would be for an expensive item like a car and those purchases usually take much longer today anyways. Finally, if you are using bitcoins on the Internet instead of POS, confirmation time doesn't really matter.
Merchants love bitcoin because they get their money right away too. Credit card companies take a long time to actually send money to the merchants (as you pointed out).
Yes maybe, but do you think that it will impossible in the future to double spend the bitcoins with new technique / with and without fees? And some tricks?