If people are interested in getting more data on why monopolies and monopsonies are bad I'd recommend "The Myth Of Capitalism" (https://www.goodreads.com/en/book/show/40751646-the-myth-of-...).

It made a compelling case for breaking up large corporations in the interest of reducing inequality (via more competition and reduced consumer prices). However, it's the only book I've read on the subject so am unsure if it's a widely held and reliably informed view.

For commenters that are wondering what world we'd be living in with functional anti-trust laws, the book suggests we look to the US between the late 1930's and the early 1980s.