Here are some that I can think of on the top of my head:
- It's volatility in price. Hence holding your funds entirely on bitcoin is a huge risk despite the advantages.
- Very unsafe for careless and technologically-illiterate people. Logging in to a phishing link? Say goodbye to your exchange's funds. Forgot to list down your wallet's seed? Say goodbye to you wallet's funds.
- Unable to operate offline or non-electronically. This is a downside on more on the 3rd world countries, whereas most poor people can't even afford smartphones or any device that can hold bitcoin.
- Not-so-good transaction fees and time. Transaction fees and times are definitely alot better now compared to months ago, but I still remember the days when txs were almost instant, with very very low fees.
- My personal opinion: The name "bitcoin". I personally think it sounds like something a person involved in pyramid schemes and Ponzi scams would use.
This here pretty much are all my personal concerns as well, apart from the last point. I think that bitcoin is a perfectly fine name and i don't know why you would associate that with some sort of pyramid scheme at all.
But, volatility and bitcoin being very technical are problems that will be solved as it moves along into the future. More applications such as exodus will simplify the user experience of bitcoin, and as more merchanst accept bitcoin its value will stabilize naturally.