Question as no experience person

I know that there are people here that managed to get into better trades: Plumbing, HVAC, Electrician etc.

People diss roofers, rebar and masonry.

Where i live, i can get a labourer roofer in a day, but i read so much here that if would like to start the Skilled Trade life. ALWAYS AVOID: roofing, rebar and concrete finish. is it that bad to start at those specific trades?