- Too complicated for masses
The world is going more literate, and the more people will know more about bitcoin. But, with bitcoin having a marketcap of over $500 billion, then who are the masses that are using bitcoin, don't you know they are the masses that are using bitcoin? But, although, yet little fraction out of total people on Earth are using bitcoin, which means more people will still make use of bitcoin in the future which will drive its price to all-time-high.
- No 100% reliable back-up protection if private keys are lost or stolen
Seed phrase can also be the backup, it will be easy for backup than private key. The privacy is for us to be our own bank, then the responsibilities are ours.
- No charge-back option (this is both pro and con)
Explain yourself better.
- Not enough big merchants
We do not have this as an issue, time will tell. Also do not see bitcoin only as money, it is also an asset.