Not mandatory, but I'd say a very desired feature. I myself have been into situations when I'd sell my crypto because I needed money, even though that was extremely unprofitable, plus the fees were high. I knew that wasn't time to sell and I wouldn't have done so if I was financially secured otherwise.
I've learned my lesson and now I only buy when I'm confident that in the nearest future I won't need that money and won't have to sell.
Nevertheless, one can make a profit from short-term returns with alts, or daily trading, I don't think financial stability plays such a big role in these cases.
Not all would really be having that kind of situation on where they do have always back up funds in case if things doesn't really tend to happen on what they had expected.
Even myself had put through situations like this on where I do need to sell on lose because I do really badly needing some funds for some personal reasons or emergencies on where it do
sucks when you do saw that theres some significant rise.
Situations like these are inevitable and cant really be avoided but if you do have funds allocated for such situations then I don't see for it to happen.