No doubt, Bitcoin is a great retirement option. But it isn't really hassle-free. It isn't actually 100% smooth and convenient all the time as you may want to portray it. It has its own share of hassles so to speak.
Bitcoin isn't really just inside your pocket and you don't need to do anything to use it. You will probably have to convert some, so you still have to deal with the banks and other third parties. There might still be delays and other glitches.
Bitcoin is also not an anytime money. Its volatility means there are good and bad times to transact.
As to possible threats and harm, you're actually not free from them just because you use Bitcoin.
My point is that while Bitcoin indeed makes our life better, it doesn't actually make it ideal.
I agree.
Tho, we can't deny it that it's better than using fiat as your retirement plan. Withdrawing it in a bank ain't that hard as long as you're withdrawing decent amount, unless you're going for too big cash that will make them suspect you on where did you get such large amount of cash, but I think it will still vary on what kind of work did you do before you retired, if it paid well, then I don't see any problem withdrawing big cash.
The harm that could get to you is very minimal, unless your relatives or friends are bad people that want to steal your Bitcoin, or if you're bragging it on social medias.