In my view, this opinion is absolutely wrong.
For my part, when Dota, for instance, was just a Warcraft map and wasn't that popular, I myself participated in tournaments where the prize pool was formed from entry fees contributed by the participating teams, with purely symbolic amounts of 100-150 hryvnias.
Esports is, first and foremost, competitions in computer games. Prize money is merely a consequence of a gaming discipline's popularity.
Many tournaments are held on HeroesWorld. Therefore, it can be argued that Heroes 3 is an esports discipline.

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