Short version : the labor aristocracy, but also it's an investment that pays for it self.
Long version :
At present the masses have very low income and wealth. They can't afford to pursue activities that don't pay a wage. Hence why they don't seek out higher education, work for free in unpaid internships or pay for training and experience (like in OP). That condition preserves the scarcity of skilled and educated labor.
Highly skilled and educated people can make a lot of money because of that scarcity. However it goes beyond that, when skill-training and education is inaccessible enough to the masses, the "edu-skill-status" can be perpetuated generationally and you get a sort of political effect that is somewhere between a caste and a guild that will lobby the state to act on their behalf to reproduce their status as an elevated social strata. Sometimes this is referred to as the intelligentsia and the managerial strata in socialist econ-theory.
If you payed people a normal wage for the activity of training skills and getting educated, then this entire field of activity would open up to the masses. There would be a huge increase in the supply of skilled and educated labor and hence the overall price for that type of labor would go down. The labor aristocracy would loose relative wealth and status, but the larger supply of that type of labor also means that their workload would decrease and their quality of life would improve, so this is not really a bad deal for them. It also means that more people can work on enhancing the productive forces so that the economy can produce, more better and cheaper, which translates into everybody getting richer in absolute terms.
It's unclear to me if capitalism can do this. But it seems plausible. The capitalists would be paying for this now , by hiring people and paying them a wage for up-skilling and educating them selves in order to get more and cheaper skilled/educated labor a few years down the line. However they don't do it, they just complain about lacking skilled/educated labor. Capitalism actually has a tendency to do the opposite and cause a "de-skilling" of labor. I'm not sure if this is only the case in neo-liberal capitalism or not. I only have data from recent decades which is all from the neo-liberal phase. The supply of low skill labor would also go down because off all those people that exit the low skill labor market when they enter into training-employment, maybe the bourgeoisie has a priority to maintain the supply of low-skill labor. It could be that capitalists are caught up in imperial logic and they are chasing the goal of poaching labor from other countries. Given the steeply rising cost of maintaining imperialism that's not rational but political momentum and ideology can prop up irrational policies for a while. Sentiment might play a role too, the capitalist class hates the masses, they are not subtle about expressing it, and they might not like the idea of enabling "the plebs" to do self-improvement.
For sufficiently advanced socialist economics that employ some kind of a planned economy this is not complicated at all, there it's just a variable that gets optimized. Basically you keep increasing the number of up-skilling/educational jobs as long as it's yielding a net positive effect on the economy for example by raising productivity.