All of you just answered based on low possibility or the company's reputation or being a hard thing to do, or they will go to jail and stuff.
I don't know why do you think it is a very hard thing to do?!!
if the company is based inside the U.S, the FBI for example can get them only if they remain in the country.
It's so easy for Coinbase to do that, presume I'm the owner, I get out of the country today and go to a country like Russia or Iran, then I transfer all the coins in our database of wallets to my own physical wallet, then I convert them all to different currencies and store them in a Swiss bank, and then I shut the website down or just leave it be after clearing the database. now who can catch me? what can they do? easy money in one day.
I had to wait years to gather that much money, but now I have it in a day, and now I can start another business in another country without any trouble.
and about the "Hold your own wallet some place safe" thing, isn't that prehistoric?!!!
in the past people were putting their money under their pillow! and the banks were invented to change that and keep people's money somewhere safe for them and guarantee their money by official documents.
and now again, you are telling me I should hold my own money in my own wallet in my pocket or under my pillow??!!!
while there are so many benefits and services banks provide for us (like Bank Checks, Loans, setting withdraw limitations, and so many other services)
what does a wallet of bitcoin in your pocket do for you??!!!
what if you loose it? what if your hard drive break, and so many other what-ifs.
I think Crypto Currency is an idiotic idea in the first place.