If you want research money you have to write a research proposal. Promise the moon on a stick, and maybe you actually get the money! The success rates for pretty much any major funding agency are minute, but if you don't try, you won't get a penny. So the stubborn keep writing proposals. If you promise the moon on a plausible stick you might have success! And who decides whether the stick is plausible? Well, that's us. Proposals get reviewed pretty much as journal articles are; they get sent out to experts in the field, who give their detailed opinion. It's slightly different as if you review an article: you do that so the authors can improve it; a proposal is the end product, so you only judge it.
I was asked to review a proposal recently. It's quite a responsibility! I won't say what it was about (okay, there were foraminifera involved), or who by, or what funding agency had asked me, as I stayed anonymous. I also don't know what happened to it, although I can guess. I liked the proposal and I hope the authors get it funded, but I did see flaws in the proposal, and I did point these out. And as soon as there is any blemish on a proposal the chances of it getting funded are rather slim. Should I have not pointed out the flaws then? That would make the system collapse. One should be honest. And there would have been several reviewers anyway.
Part of me still feels like the excited 17-year-old who went to university for the first time, but it's things like this that make you realise you are actually a professional whose opinion matters in the world. It's a lot of responsibility but it feels good all the same!