Mostly to get a few miles of steps in, honestly. Throughout high-school, undergrad and grad school I worked as a server and it's just become something that helps me stay sane (and I love the food we serve tbh).
For what it's worth, working as a server can be really helpful for loneliness though - at virtually every place I've worked, the coworkers become very close and good friends as we all commiserate together throughout the shift haha
Serving did help me a ton with getting comfortable speaking in large groups of people; was a huge benefit - being able to strike up a conversation with just about anyone, build rapport and make a connection has been infinitely helpful in my personal and professional life.
I'm sure there is a better way to frame this but when I approach a table of guests I kind of pull from a "rolodex of personalities" to instantly make them comfortable and build rapport (since it's kind of awkward on the guest side, too, if that makes sense) - it's like having hundreds of small, genuine conversations a day. Some tables can be toxic but they are quickly forgotten by another group who are incredibly fun to wait on.
Definitely recommend trying it out at a non-corporate location if you have one! I work at a Rock Bottom which is a definitely a corporate owned brand but it's a lot less suffocating than a chain like Applebees, Olive Garden or others in that vein. A local place will give you a lot of agency and autonomy on how to manage your tables - the owner at the Mexican restaurant I worked at would walk up to your table and tell them to 'get the hell out' if they were being hostile towards you