My guess, greed. In AoMH you need 24.000 valentine chocolates (valentine event currency) to get the 120 tickets for Maus and iirc you get around 35 tickets every 2 weeks. So if you start playing right now you must login every day, farm 17.000 chocolates AND get Maus to level 4, which also takes money and/or time. I leave my pc with a macros running before I go to sleep and I get like 500 chocolates in 8 hours so... good luck (I don't know if there's a fastest method though).
Tl;dr: If you are new, pay $1 and get Maus or prepare to farm for days non-stop.