@serpstat #SERPStat_Chat A2
Yes/No
It's not the quantity as much as the quality.
You can most definitely have too much crappy content,
and not enough quality content :D
But huge volumes of content can/does come with (the potential for) issues,
including cannibalisation.
>>>

@serpstat #SERPStat_Chat A2.2
>>>
The chances are, if you produce around a specific topic, and product a lot of content, you will keep touching on the same topic (or more likely, subtopics).
If care isn't taken, this can potentially lead to multiple pages being relevant for the same query

@serpstat #SERPStat_Chat A2.3
>>>
Other issues include maintenance/upkeep.
Housekeeping is something many miss - and can result in a build-up of irrelevant/lower quality content (as well as potentially self-competing).
For Mega-Sites, there is the consideration of Crawl Budgets.

@serpstat #SERPStat_Chat A2.4
>>>
Most people don't have to worry about such things,
but when you have hundreds of thousands of pages,
G will already be crawling X number of existing URLs.
Getting "new" stuff discovered, crawled and indexed can be more challenging without good planning.

@serpstat #SERPStat_Chat A2.5
>>>
There's also costs to consider.
Not just getting the stuff created and edited/approved,
but any resources required (images, expert time etc.),
and even the risk of high-traffic resulting in additional hosting/CDN costs etc.
(Mega-Sites aren't cheap)