Basically, anyone has the right to sell their Bitcoin, including Jim Cramer. Well, he might regret it, especially if what he fears doesn't happen (the threat of quantum computing) in the next few years, but he should understand that his decision today will determine his future, and he should understand all the consequences.
Yes, but maybe he can use it to invest on an asset that will also increase in price very well. It might or might not regret it, depending on what he used the money to do. He can use it for business and not regret it if the business pays out very well.
By the way, I am just a little puzzled: why is he so convinced of the threat of quantum computing that he is selling everything ? He should have kept some of his Bitcoin, or half for a long-term plan. Because, I think it is a wise decision to leave some Bitcoin to invest, and it is wise not to put so much confident in what might not happen.
The Coldcard issue recently might be the reason. He can think what if quantum computers just brute force a private key and what if it is his private key. That the money will all be gone like what the Coldcard thieves did. But that is not a good point to sell his bitcoin.