honestly, a lot of players already established strong accounts themselves...
i'm not as strong as the one you mentioned, but i'm already quite invested in my account given i got 11 6* girls and my power is about 430k normally and about 850k whaleship
it's honestly not that hard to get strong, but it can get a little grind heavy. but if you know what to do and who to use out of your collection, runs can take as little as 30 seconds.... i've literally done one in 15 seconds with on one of the 100 stam manyu missions before
and keep in mind, i started less than a year ago (when Trailing and ghost weed appeared for the first time... and we just got the rerun not too long ago)