Each individual risk Apple takes is small - they didn’t develop the M1 from scratch; they have years of iPhone and iPad processor development under their belt.
The risk of Apple deciding to design their own chips was massive.
Apple started working with ARM in the 80s, eventually used in the Newton. I don't know that they did design directly, but they influenced the changes that became ARM6.
I would speculate that the Palo Alto (P.A. Semi) acquisition is what kicked off this round of the Apple semiconductor (r)evolution.
The individual risks are small now, but they weren’t when Apple was recovering from near death.