Every nonprofit on the planet has the long-term goal of having an endowment large enough that they can focus on their core mission rather than bullshit fundraising drives. In order to do that sustainably, they need to have an endowment approximately 25x their annual operating budget, plain and simple.
Okay, so you're saying that Wikipedia will raise another $9.5 million* and then stop, right? If they do that, then I won't complain.
Of course, they're almost certainly not going to stop. Instead, they'll just increase Jimmy Wales' compensation (among other silly things) and keep badgering users, because that's what all non-profits actually do.
(* 25 * $2.5M = $62.5M, $62.5M - $53M (the amount they already have) = $9.5M still needed)