Few commercial photographers shot 35mm, in fact those I knew didn't own any 35mm cameras. 35mm was mainly used professionally by newspaper photographers and amateurs.
I mainly shot 35mm colour slide and B&W at rock concerts, and snapshots on E4 later E6 films. You couldn't compete with people using 120 and LF with a 35mm camera where it was practical to use a larger format..
Before I moved to MF & a couple of years later LF (1976) I was shooting portraits commercially on 35mm but these were more environmental portraits, people in their natural surroundings.
That was then, now it's very different, some of the work I do can't easily be done on film - the specialist films went a few years ago (and I don't want to experiment again). Clients want digital files quickly, no delays while negataives are processed and scanned, and I always do my own processing and after shooting a rock concert would do a C41 and E6 run the next day. There's a lot of work involved and that cuts potential earnings. So in my case I decided if they need fast digital results then an all digital work flow was the best option.
That leaves more time for shooting personal work and some commercial work on film, and I much prefer film.