I do not think it is good to think about it as a "steal". Every move you do should be well thought of and without a plan a "blind steal" mindset can be EV-.

Reasons for raising preflop

- Build a big pot when equity is high or opponent is weak on later streets.

- To isolate players, fewer people to flop.

- To increase likelihood of getting a good position post flop.

- To manipulate players (set them off, stop them from stealing, make them uncomfortable)

- Fold equity- chance of winning pot without seeing a flop.

- To gain initiative on flop. Preflop raiser has psychological advantage and can represent bigger hands post flop.