why are right-wingers so much more likely to do adventurism?

Unofficial sanction and support from the state and capital as long as they are targeting capital's enemies. Plus, their goal is to reinforce the existing status quo of wage slavery and race terror. They're moving with the stream, it's easy to achieve white supremacist and capitalist goals by murdering minorities and labor organizers.

Unless a Leftist has gone full nihilist then random violence doesn't serve any useful purpose. The same is not true for the CHUDs.