I have one sim with the "own 5 top level business" LTW and want to make this guy the richest sim around. I hear people make businesses earning 10s of thousands a day. What is the most profitable business and easiest to start out with. I don't intend to use any hacks/cheats.

I would start with a bookstore, even though the profit margin is low; bookstores probably have the lowest overhead of any shop and provide a good background for gaining perks useful in subsequent businesses.

You never make any money at a bookstore though. My best earner in my hood currently is my car lot. I started off selling them for cheap to build up the business level, then put the price to average. On the sports cars you are making a fair amount of profit even when selling at average, whereas you'd only make a few simoleons on an expensively priced book. For the least overheads, try a hairdressing salon- the chair is the only outlay, plus any wages. the rest is profit, and you don't need to restock.

I hear that the pay-per-hour ticket thing is easy because theres no restocking, its just harder to gain stars, maybe I could start out selling random crap to get the level up and then turn it into a pay-per-hour thing.

once you get the gold sales badge use dazzle, for average priced and lower it makes the sale, for more expansive if gets the buy meter close to a sale. it also gives stars, but kills your energy. my laptop has an issue with graphics so it starts to glitch if i travel so i hve to use maxmotive alot, but if you dont have to take breaks and are open 24/7 you make alot of money after a while.
cheat or don't but the more household sims working jobs, the less employees needed so less money goes to the payrole.
Later.