If your workplace has good safety standards it's not as much of a problem these days, I'd rather wear a respirator at my job working with fumes and dust than sit at a desk all day and fuck my back and eyes up. Though I'm fucking my back up too probably, but if you don't overwork yourself and use proper techniques even manual labor doesn't have to be so bad for your body.
Idk plumbers, electricians, contractors, etc make a lot around here. I'm sure they usually have business overhead that factors into their hourly rates (like $100+ an hour here in Seattle). Or if they work independently, they'd still need to pay taxes, insurance, health insurance, licensing, etc., but assuming they make $60/hr after all that, that's pretty good.
I'm a contractor. I work in hospitals where it rains money. They charge $120 an hour for my services. By the time all the hands get in the pot, I get very close to $100 less per hour.
What do you mean by cutting off connections? To escape this hellhole we need connections more than ever, some people can manage to survive on their own off the land but humanity works better together. Our economies and societal structures are enforced by parasites but there are many people that want to build positive things.
I know electricians in their 60's that are insanely fit. Like run up and down flights of stairs all day no issue fit. They take care of themselves and always have, and never stopped moving. I think manual labour with a proper diet and sleep schedule is one of the best things you can do for your body.
It's also because a lot of blue-collar guys are heavy smokers and drinkers, which ages people fast. It's not so much the work as it is the lifestyle. The work can cause injuries as well, but being injured isn't the same thing as looking older than your years.