Way too simplistic view.

> increase supply

Not necessarily. Supply could stay the same.

> drives down prices

Not necessarily, if raw materials got more expensive.

> The only negatives are on the individual

You might want to have a look at youth unemployment rates. Sometimes, there simply are no jobs: https://ourworldindata.org/grapher/unemployment-rate-for-you...

Changing careers reduces your income and your purchasing power. If it happens to too many people at once, standard of living decreases.

You simply neglect demand in your entire argument.