We need to make a distinction between individual opportunity and societal opportunity. As and individual you can study hard, become an engineer, save a lot of money and retire early. No problem with that as long as you have adequate intellectual capability. It is not, however, possible for ALL people to do so at the same time for quite obvious reasons.
You're right, not everyone can, or ought, to be an engineer, or doctor, or lawyer (please, we have enough of those leeches) or accountant. But one need not earn a professional degree to do very well.
Were I truly smart about it, I should have skipped 4 years of paying for an education and gone straight into the trades as an apprentice. A few years ago, the utilities here in the PNW were griping about how they couldn't find enough linemen. Paid over 100k / year with OT for journeyman level - get a few storms where you're working for a week straight, and you're into double, triple time after a while, especially if it's over a holiday.
Heck, in my company, the shop guys and gals hit top scale in 6 years and average 85k / year - not bad for taking a few week "beginning XYZ manufacturing" course and then working your way up. Engineers, yeah, we end up higher and there is no top scale, but it takes a lot longer and it's largely merit based. I quite possibly should have gone onto the assembly line - I would have ramped up my income sooner and faster (that whole time value of money, plus NOT spending 4 years tuition, while earning 4 years of pay).
Hell, my car mechanic charges $89 / hour shop rate - not bad for a blue collar guy with a couple years of trade school (if that, often times car mechanics OJT it or can take classes in high school) and a whiff of business sense to open his own shop in a semi-decrepit old gas station. Always has plenty of business since he's honest and does quality work.
I won't even mention a buddy that started his own lawn care business as a teenager. Bought a used lawnmower and weed whacker from C/L cheap. Pushed it by hand through his 'hood to jobs until he saved up enough of his earnings for a truck, then could take on more than pushing distance clients (amazing how that works...kid never been to B School and understood how you need to re-invest earnings into CAPEX to grow the business). One doesn't need to be too bright to mow lawns.
But hey, woe are all those people without an education - there's no way they can make it, they've all been kicked so damn hard for so long its not worth ever getting up. Yep....doomed I tells-ya. DOOOOOMED!