Actually, that's how I "accidentally" played my first ever Sims 3 sim. I installed base game and Late Night, thinking I wanna be a guitarist and live on tips. I stumbled upon a few celebrities friends and became one myself. Then the manufacturers keep sending me expensive stuffs, cars, furnitures etc. I just sell them off whenever I needed money and became quite well off. If those are not counted as opportunities, I also attend some cameo sessions and made several cool 5 thousand simoleons.
I never did earn a lot from tips. =( Nobody watches my performances.