You can manage if you know what to do to stay on top levels if you do everything, even going into the jacuzzi helps. The guy with jonin probably didn't do everything and the f2p one did. Being F2p is hard and requires patience and time, remember everyday counts & doing ALL events gives exp daily so if u max that out and the jonin guy doesn't you have an option. As a small expender myself (i think i've invested 20$ for just returns of coupons) im ahead of all the F2p players with other 2 guys just because we do everything and we have just catch 2 of the big expenders (there are 3 in the server) in level and one in power, ofc if they are big big whales there is nothing to do, it will just take more time.

SAVE EVERY COUPON YOU HAVE FOR LUCKY BOARD OR SOMETHING YOU WANT TO FOCUS ON

PD: First weeks is nothing in terms of level, you will notice that like in 2+ months where everydays exp really makes a difference. With power is different, you have to go all power in all events and you will prob be behind always against big expenders but way ahead of F2p players, with time (a lot of time) its either that space becomes smaller or they go way ahead but expending way more, time is everything for f2p players.