If someone is motivated enough to attend protests, they're motivated enough to go vote.

Many of the people who go to protests have lost their right to vote.

Not sure what that means. Mostly ordinary citizens go to protests. Not aware of any group paying felons to protest. Speaking of, is Trump allowed to vote?

Attending public (peaceful) protest is valuable. It shows that people with that view point (whatever it is) are not alone. It encourages more people to get involved.