For me, the top 10 problem is:
1. The price goes up and down too fast! It was at ~$700 when I first heard of bitcoin, once down to $200 (that's when I had lost confidence in bitcoin and started selling my old account) and now at $700+ again...
2. Negative exposure to the public. e.g. my computer have been hacked earlier this year for some
BTC1.2 ransom or all data is lost... At least this incident made my family thinks that bitcoin is a really bad thing... (We haven't paid a satoshi to the hacker and recovered our data though)
3. Low adoption rate. In my city I have never see a shop accepting bitcoin, and I have only seen a shop with bitcoin symbol (bitcoin exchange shop?) outside when I travel to the next city...
4. Very expensive transaction fees. It was
BTC0.0001 but now a higher fee should be paid or the tx will not be confirmed within few hours... For
BTC0.0005 (~$0.4 now) can buy me a pack of candy but I'll now have to 'burn' it away as fees... Especially for my faucet payouts, this high fee already taken away a huge percentage of my earnings
5. Hard to memorize bitcoin addresses. If Peter told me he had BTC address 1ooo15cT8HTdBir1nKUnw4EDPsa2tkszK and Mary have address 1ooo2rqenMxrgXgz4JkcWs4cdhRBYdhQL, I would have remembered only the first 5 digits of them (because they looked like 10001 and 10002)... The rest of the digits looks like random so I cannot send BTC to them unless I can copy-paste them... (The address book in wallet can solve this, but what if I send from exchange?) (These 2 addresses are all owned my mine and they are vanity addresses so the first few digits are recognizable, other addresses have all 34 digits (or 33, BTC addresses with <32 digits are rare) almost random and even harder to memorize
)
6. Very large blockchain. I have considered downloading the full bitcoin client but the blockchain size of even 10GB have scared me away from doing that back in 2014... Now the blockchin size is approaching 100GB and would have take up half of my C drive (in fact I have only 80GB of free space now and still decreasing!).
7. Long block time. Even I have paid enough fee so my transaction is going to be confirmed in the very next block, it still take an average of 5 minutes for 1 confirmation... For sites requiring few confirmations the time needed is even longer... I have once waited more than an hour before a network block is mined so my tx cannot be confirmed in that hour!
8. Mining difficulty is too high. For a practical computer, earning from faucets is much more faster than mining bitcoins (or even CPU-friendly altcoins). This makes the distribution of new bitcoins concentrated to those who invested for ASICs, which pollutes the environment while using electricity for mining...
9. Satoshi's 1 million 'premined' bitcoins. Although they are not in market yet, once they do, it will crash the price of bitcoin by a lot. Also if satoshi decided to sell his coins, others will think that he have lost confidence in BTC and hence dumping them too. By this Bitcoin will worth nothing but just a part of the history.
10. Crashing of private keys. Although this will not happen in the near future, this will happen a day. After this once can spend BTC belong to others, which will make the system insecure.