Hair requires sebum for moisture. Sebum requires hair to aborb into. When someone buzzes down their hair there is suddenly no hair to absorb into, but still the same amount of sebum being produced, the sebum builds up on scalp and clogs pores, accelerating hairloss.
I have known countless people who had diffuse or partially receding hair for many years, hairloss was stable but then once they decided to shave or buzz down they lost a lot more coverage and head is far more shiny. They then can't grown back to where they were before buzzing down. No way back, apart from a transplant (or possibly deeply exfoliating your entire scalp)
You could have hairloss which is just about manageable for years but once you shave down there is rarely a way back.