RustFest sponsors folks who couldn't otherwise attend with tickets (and sometimes travel and other things, I forget the details). This includes students (IIRC)
They also have tickets on the site which you can buy to add money to the sponsorship pool.
> We believe in diversity and would like to provide support to people of many different backgrounds. This includes, but is not limited to people who belong to one or more of the following groups: people of color, women, nonbinary and gender non-conforming people, disabled people, people with mental health issues, and LGBTQIA+ people.
Scholarships are a pretty normal thing wrt conferences.