You and probably 90% of the current wow playerbase does, most of us are atleast 20+ and I doubt any parents are still paying for subscriptions at that rate
I don’t have time to raid either and you can go beyond mythic 6 with your friends, you just need more practice.
No, you don’t need to farm mythics all day, or even one per day to progress, but if you do mythic’s with your friends (which is the best way to do them tbh) and if you keep going with relatively the same group, you will improve, even if it’s just one per week
And lastly, if you really never get beyond mythic 6, why would you need gear that surpasses mythic 6?