This has been a point of contention all the time. Regulators want to shrink the market size as much as possible, and companies want to expand it as much as possible. This is not a way to determine monopoly.
Re:The antitrust case against Google
by peterwoerner on Friday June 12, 2020 @01:07PM
(#23501321)
The quote was referring to the way the company describes themselves in e.g. 10Q briefings.
“Anyone that has a monopoly will pretend that they're in incredible competition. If you're a non-monopolist, you will rhetorically describe your market as super small, you're the only person in that market.If you have a monopoly, you will describe it as super big, and there is lots of competition in it"