Basically comment spam is OVERPOWERED.

a while ago he spammed like every post to join his contest to great success. After that every one of his posts kept on getting to rankings and making a positive feedback loop.

I used to personally do it to a much lesser degree, and I was one of the most popular accounts on the app for a while, and let me have my post be the most popular of 2020 rankings.

There's 2 types of strategies which both work really well.

1. Spam every post you see to get people to see your post. (Annoying)
2. Just spam generic stuff on each post such as
Nice, cool, and awesome. (Much less Annoying but very see-through. Less effective)

Of course you could also be just very active in comments and writing good dedicated comments, which works sorta well especially long term.