Waiters in high-end restaurants can make a career out of what they do.
There is a restaurant in the DC area called L'Auberge Chez Francois where most of the waiters are long-term employees of the place, some with 30 years at that restaurant.
When you're waiting at a place where a table for 5 can easily spend $1000, your tip from that one table will be $200.
As a waiter at a 'moderate high end' restaurant I could earn a month's rent in two nights (Sat. and Sunday). That was when I was in college and I was living two blocks off the beach in a 900 sq. ft. apartment.
We had several guys who were 'professional' waiters, they did OK, but usually spent money fast and furious... gambling, drinking, fast women and slow horses.