Tekken 7 has been too reliant on Treasure Battle instead of a traditional vs. CPU mode, which would be fine if it weren’t for the gimmick battles (turbo, double damage, aerial damage battle) and bosses (most of which can 1-shot you with their Rage Arts). Also Tekken 6 has scenario campaign, which is considered the best single player mode in the series, so maybe you should play Tekken 6 at some point.
Also the last comment isn’t really true, I’ve seen plenty of casuals online, so losing over and over again is not guaranteed if you know where to go. Also paying for XBL Gold lets me play Warframe and Path of Exile without needing a gaming PC, which is good since I’ll clearly never have one in this lifetime, so I wouldn’t call it shilling (at least not in my case).
TL;DR version: Play Tekken 6’s story mode, it’s writing may suck but it’s a proper single-player campaign. Also you can unlock the other characters for use in it, similar to Tekken 3’s Tekken Force mode.