Are you in the US?
In the UK after 6 weeks I can believe that, (so if you say you've not played in 2 weeks, I'd assume you were in the states, idk) I'm lvl 26 and about 50k from 27 atm and I have a job (only 3-4 days a week) that has prevented me playing as much as I could and I don't own a car to travel to good nest sites or anything. Also I believe the game was a little less polished when it first came out - eg. weren't commuters cleaning up with travel distance as there was no speed limit on it at first?
But in July there were people with 3k+ Dragonite on multiple gyms in my neighbourhood (one by the name of Pok3mongoKing, which I always read as Pokthree Mongoking, but anyway...)
As you need to be level 29 for a perfect IV Dragonite to hit 3k CP I will struggle to believe these players were not cheating in some way or another. I "power level" as best I can, spent a few ££s on coins to buy multiple incubators (hatched 275 eggs so far, up to 120 in my Pokedex) and a few lucky eggs for batch evolving (on top of the ones you get for levelling). I can happily believe people have got twice as much XP as I have (which puts them on level 30, with 400k or so to 31) in the time available, but much more than that and I call shenanigans
Theres no way anyone hit lvl 30 after 2 weeks of playing