She's a shrine maiden, donations is her only source of income. And given that people don't visit her shrine (and those that do practically never donate), not a steady one. Big events are her only chance to get any serious amount, but those are few and far between. And given that she's not all that good at her job and suffers failures frequently, she has to try even harder. So she tries to grab whatever chance she can (although never to outright "scam" levels). Since it's pretty much her own SURVIVAL that depends on her success, of course her approach would be aggressive about these things.
Also, do keep in mind that the chapters come out slowly, with two months in between, and stories depicted there usually take place around the time they come out. WaHH focuses on times when she needs to act, not on idle everyday life. She's probably her usual carefree self all that time off-screen.
Well, there's also a theory that WaHH is shown from Kasen's perspective, and as chapter 5 shows she doesn't have an accurate and unbiased opinion on Reimu.