You're right, but the price of the crypto used for the bet, is also an issue, if it falls during the period, you'll get coins that worth nothing in 4 years.
There are multiple risks. Obviously the cryptocurrency exchange rate can go down, just like what happened during 2014-15 period. But a greater risk is the gambling site itself getting closed without any warning. I am active in this forum for almost 4 years and I have seen this happening in front of my own eyes. Many of the gambling sites, which existed in 2017 are no longer active. Most of them vanished all of a sudden, taking the customer funds with them.
There are indeed sites that had closed up their doors but only a few of them did really do such thing and still there are old sites which are more that 4 years old
are still running up today.It all matters on the demand and its just normal for them to close if they aren't really getting much players.
About on probable scams and frauds then it do really happen that's why we should really be careful even though we cant tell it initially
or wont know on what would happen.