Coincidentally, I had this conversation with a friend in his late thirties a few months ago.

Here's the short answer: you aren't too old. However, your total lifetime earnings as a pilot may well fall short of your total lifetime earnings as a welder.

Why? Well, you'll have to borrow money to get your initial training, and your pay as a new-hire pilot will be low for several years while you build time and get the college degree you need to land a job at a major airline. The good news is that if you can hire a responsible manager to run your business (your wife, perhaps?), you won't have to meet your financial obligations to your family based on your pilot salary alone.

Practically, there are several good companies and universities out there with solid flight training programs. I suggest that you look into ATP Flight School (https://atpflightschool.com/equipment/index.html). I earned my Airline Transport Pilot Certificate and FE Written there many moons ago and I was happy with my experience. Once you get that done, you can take those certs and your real-world experience to your local community college or state university and bank college credits based on work you've already accomplished.

Ok, so now you've done all of this, and you're working at a Regional for, basically, ramen money. [Remember: Regional Airline pay scales at the new-hire level are designed for single, 22-yr-old recent college graduates who are sharing an apartment with five other people.] You're taking a couple of classes per semester on line or through some other type of flexible program, and you're also doing some welding &/or leading the person you've hired to manage your business. That child you're looking to inspire? One the one hand, you aren't going to be seeing a whole lot of him. On the other, he'll see you setting an example as a man who sets goals and achieves them.

On a personal note, I was in a slightly different position in my late thirties. I was doing well in the world of systems engineering and technical program management, but I hated my work. I did the math and found that my lifetime earnings would take a massive hit if I switched tracks to become an airline pilot. I did it anyway, I'm now a captain with a major airline and I'm happier than I've ever been. I'll take happy over rich any day of the week and twice on Thursdays.

Oh, and one of my kids came up to me the other day and said, "Dad, I want to be an airline pilot." I can't wait to take him flying.