1. Low Transaction Costs (with Free Copper Free Transactions)
2. Convenience in transaction: You can transfer or receive electronic money immediately without intermediaries such as banks, government, ...
3. High security
4.Creating development potential for e-commerce.
id like to correct some point that you'v already given .
1. not all alts are low cost when it comes to transaction fees. afaik , the cost fees will only depend on how big or small the alt is .
2. all cryptos can do that not only alts or btc . cryptos are decentralized which means they are independent .
3. all cryptos are secured . your safety will only depend on how you handle your coins .
4. i think all cryptos can also do this .
imo , i think altcoins do only have a slight advantage compared to btc , and that is alts do have thier own usage not only for currency or an asset use .