• Is there any reason to add gambling tokens to my crypto portfolio?
I don't see any reason for you to buy these tokens from casinos, for example if you buy bitcoin, you will be expecting that in 4 years the price will go up a lot because there will be the halving, also the price in the past managed to reach $68000 and it just dropped a lot because the entire international market is going through a financial crisis due to the war in ukraine, so there is a high probability that this war will end sooner or later and the price will go back to 68000$ or more, so it's worth buying bitcoin
What drives their value?
agreeing with the same thought I wrote above and at the same time answering your question, the truth is that there is nothing concrete that could lead to an increase in the price of these casino tokens, you can sit down and do research on your own and then decide ask what's special about these casino tokens you won't find anything
Do they appreciate in value just like other altcoins whenever we are in a bull market?
see this:
• If you are in my shoe right now, what gambling token do you think you can take a risk on and add to your crypto portfolio and why?
my answer is simple: no, this is not worth the time and risk, look for other altcoins or bitcoin to invest in, you said yourself that you had already invested in cryptos, is that not enough?