That's blatantly wrong. Hydro stands out in the data as being the cheapest reliable carbon neutral option (wind and solar aren't reliable, and when you factor in storage to make them reliable then they're not cheap).

Hydro requires large sums of capital to get started, destroys entire valleys, is only viable in a limited number of places, has significant risks if not maintained, and isn't energy dense in the slightest. Nevertheless, it's cheap and it's carbon neutral.

Run-of-the-river hydro in all but a handful of sites tends to be quite dependent on rainfall levels. This means production levels can vary quite meaningfully both seasonally and more importantly year-to-year.

It's definitely reliable in the sense that hydro stations can basically last forever if properly maintained (there are plenty of hydro stations operating today which are more than 100 years old) but it's not quite a silver bullet.