There is some truth to this- but the world is entirely run by people who believe they can personally effect change through their actions, everyone else be damned.
I definitely support asking our governments to pressure their government. But I wouldn't ignore the fact that people in Belarus are be the ones that might be able to affect real change in Belarus.
Separately, I would expect American sanctions to push the country towards increased trade with Russia and China -- who are both allies of Lukashenko.
on individual level the best actuon I can think of is donating to help folks that lost and eye or were beaten withing an inch of their life.
Otherwise i am not sure what you could do, perhaps we could send equipment like radios, first aid and body protection / armor? Depending on your views you coupd even post crossbows. Would they arrive through customs, assuming you know who to post them to?
Lastly, you could travel there to join the protests, but realisticaly are you going to do that?