Most people who do it are young and its just another adventure/experience, especially if you don't have kids or real estate holding you in NYC. For some, it's a great move as LA job market for CPG companies is much better than NYC so outside of design usually people make out much better in a long run. Most of ex NYC transplants are doing very good now.
Found this post on a thread on the worker transfers from the NYC office to the LA office ( @VSHDruf-1ghj ). Maybe it is true that LA provides some better opportunities, and people who move tend to do a little better in the long run, but wherever we go we can’t escape from the general condition that the company is in.