Link building strategy of this site?

Hi everyone, I'm relatively new to SEO and although I have done 6+ months of reading, I am still learning lots and have very little practical experience behind me. If anybody could help me out I would really appreciate it!

There's a site in my niche which is ranking EXTREMELY well (front page) for many semi-difficult keywords which I am really struggling to rank on the front page for. I had a peek on ahrefs and saw that he built ~300,000 backlinks to his site in around a month and has built considerably smaller amounts since.

I'm assuming he is just churning out these backlinks using gsa or something (could anybody suggest what tool he is using) and isn't using a PBN or anything along side it - why bother spending all the time and effort for a PBN when he risks them being deindexed?

I never realised 300,000 backlinks produced in such a short period would rank so well and without penalty, especially when they are all pointing directly to his money site... I was also wondering how long he is likely to stay on the front page for using this method because it has been months now and his site has not dropped at all? His url rank is currently 82 on ahrefs and his domain rank is 50, clearly entirely from spammy blog comments and pingbacks.

Finally (Thanks for those of you who have read up to here!) would I be able to challenge his website with a similar strategy for a new website that I made, and would I need to buy prescraped lists for the site or could I just leave a powerful VPN with gsa (or whatever other tool?) running to make this many in a similar time period.

Thank you very much for any help you give, it is really appreciated