Countless of people have started small and stayed small. I think it always been like that traditionally. You start a business, you grow it till its big enough to serve your niche market, and you pull in few million every year for the rest of your career life without much effort.
I used to work in manufacturing industry and this model is more prevalent in their whole supply chain. You could own 1 factory with less than 20 staff, producing 1 type of component(bolt/glue/bracket etc) and be done with it.
However, if you define successful startup, as multi-million dollar revenue organization, that's another story.