To me it seems perfectly plausible that changing the incentive structure around how a company is operated would have a way bigger impact than that.

I feel confident one can change incentives and operational practices without privatizing.

So you’ve got to put yourself in the shoes of someone who fervently believes that there is a lot of waste in the public sector.

Some people are delusional but I'm not sure the value of spending a lot of time in their shoes. In the US many people fervently believe the Republicans are "better at the economy" despite evidence pointing otherwise.

And just to emphasise, the idea of privatisation was not “let some rich people become richer.” It was to sell shares in privatised companies to as many people as possible, and make investors out of all of us.

This seems like an inefficient way to share public wealth that gives advantage to the wealthy. Let's say you're correct and the value of the shares goes from 10 to 100. People who bought more shares profit more. People with more money on hand can buy more shares. It's a large advantage to the wealthy.

As you said

making some decent money but yielding the longer-term benefits to bigger investors.

So it sounds like we agree? Privatizing advantages the bigger, wealthier, investors.