This is a common line of argument, but you will find that many tradesmen hope their children will go to college and get office jobs.
The trades are hard on the body. Some trades are hazardous. An injury or medical problem that would be a hassle for someone with an office job can be career-ending for people in the trades.
There aren't a lot of jobs for people in middle age who can't physically work a trade anymore due to age or illness or injury -- it's about as bad as being a laid-off factory worker.
The trades also get hit very hard in recessions as people build fewer things, infrastructure spending gets cut or postponed, etc. That, combined with the serious impact of medical problems and injuries I just mentioned, can make the trades more financially precarious than they seem to be.
I'm not opposed to people going into the trades, but some of the pro-trade-education arguments need a reality check. People need to know about the downsides.