As someone who's worked in the construction business, you actually gain experience from watching what the other guys do if you pay attention. There are also these things called raises, they are these magical increases in wage if you actually work hard and don't forget around.
Also your forgetting that in construction and farming is not a cushy 8 hour day job. It's 10 hours on a good day and 14 on a bad one. So you will be making bank. If you work in a construction job long enough you will eventually be taught how to operate the equipment and thus be open to much more lucrative job opportunities.
No doubt you CAN do that but not a lot of people want to do that
I've had the joy of doing framing and roofing for the past 3 summers and its brutal. That was my fathers big push was for me to go to college and get a degree so I don't have to do his job for the rest of my life. My dad has been doing the same job for 35 years now. He works 12 hour days and starts at 4 in the morning and its brutal on him, especially now that he's over 50. He makes decent money, nearly 75k a year but he doesn't wish this life on me.
No, construction is a nobel job but moving up is difficult and every contractor I've talked to during my 2 years in the lumber yard and doing delivers for them have all told me to get a job where I dont have to be doing what they're doing for the rest of my life.
When it comes down to it, construction kinda sucks and its taxing mentally and especially physically but yeah, you can do it for the next 40 years if you have to. Reminds me of the good will hunting scene