Was it actually said at any point this amateur tournament is supposed to come with any rewards, that aren't at best a trophy and an energetic handshake? Since EK said this whole subquest was purely optional, i feel doubt it's going to bring anything that'd considerably skew the balance of things in the long run -- if Ian had to participate and do well in order to afford things down the road then it'd make things quite far from optional. So i don't see this resulting in any big income spike.
The promotion is similarly not something i'd bank much on. It's still a relatively low level job, and it might come with something like +1 salary increase (or maybe slightly hither, but that's getting counter-balanced by high rents if Ian is serious about moving out and getting his own place) and nowhere near what one can get paid to prance around naked and stick vibrators in one's orifices for exclusive amusement of a rich old pervert.
Lets look at it this way...
Lena's spendings-
Family* Even though all that money gets sent to our unmet fuckhead of a brother.
Rent* Which we have to possibly cover for Louise being a cheapass bitchy cunt or force Simptardville Stan to pay.
Clothing* Gotta look your best and all, makes sense
Sex Toys* Spice up your sex life yo!
Tattoo* Entirely optional, but still look hella good.
Ian's Spending-
Cindy's one time drink
Rent* Because we have to or else Perry goes REEE.
Clothing* Gotta look our best eventually for our lovely date with Ivy naturally.
Stalkfap* Gotta support our besties. No shame in that.
Thats literally it. So, while in practice, Lena has much more options to spend money on and be possibly in the black, Ian though, doesn't really have a lot of options to spend his hard earned cash yet has atleast some money on hand. Yet Ian's supposed to have the option to get tattoos. Yet to have that be applied, even if that happens. Though I get the feeling that will be scrapped over to time constrants and be replaced with more shitty unwanted content.
So if Ian wanted to, humorously, do a Stalkfap, I can totally see some chicks, and probably some guys, maybe shilling out cash on him. He's got some things going for him, specially if he invests in going to the Gym.