Tournaments are about surviving. You have to outlast others to make the money. Part of survival is not risking risking too much with marginal advantages.
Ring games are not about survival, they're about making +EV moves. You can reload if you lose chips so it's not a big deal to lose big
hands when you only have a marginal advantage because over time you will be making money with those plays.
In other words, in a S&G if you make a lot of big plays when you're only 55% to win, chances are you're going to go busto pretty quickly and win nothing. A little bad luck is fatal.
Meanwhile, in a ring game if you make a lot of big plays when you're 55% to win you're *never* going to go busto because you'll just rebuy, and in the end you'll have an average 5% profit (minus rake).