Yep, finally got my GT7 plat as well. Not the most difficult of plats (personal opinion for me is a 6/10, and if not for the time-gate of 2 months between cars being sold in the LCD to get this damn trophy, it would be a 5/10), but still a worthy one.
This isn't the hardest... Because you simply have to finish those races. Do 2 of them per day and in less than a month you get this. It was much worse in GT Sport where you had to get 322 race finishes, over 6x more races.
The beef with that trophy is that, for people who don't like to play online, it's a "bothersome" trophy more than anything. But it's still a "fair" grind. 50 races instead of 300 is a looong way.
I personally just did the races and the races only, didn't even bother with qualifying. Unlike Sport where I had to get quite a few poles and wins.
The other negative, is that it's a "play online" trophy, so you need to pay for a subscription to get it.
Over 14 years or so of Trophies being introduced in the Playstation community... It's about damn time that developers or Sony themselves make a RULE that ONLINE trophies should not be required to get the Platinum. Server closure and having to literally pay for it are two BIG reasons for that.
Got my GT5 plat in 2011 or 2012, lost my account that had it... Started a new one years later, and now I will have a 98% non-platinum GT5 on my list of games because I can't get 2 trophies that would only require 2 minutes to get them online because... server shutdown...