Why not? You could build nuclear bombs and start using them or threatening to use them and that would be a greater threat to humanity.
Plus I didn't say you were the greatest threat today, that would be Russia and probably Iran as a clear #2, I said you were historically much worse because of your colonialist past.
The US (or Trump) is the bigger threat because it is currently actively destroying the rule-based world order, which introduces exactly the lawlessness, chaotic times that opens the window for Iran and Russia to 'do business'. Plus it is destroying the its alliances, which were part of keeping the equilibrium between power blocks in tact.
One can only hope that another power that cares about rules fills the void.