Why do people not seem to consider private grants in favor of small public ones? I have now experienced multiple instances where a group of researchers involved me in a grant application where the total awarded funds were quite small compared to the number of researchers in the group. Thus I find the benefit of a successful application very small compared to the time spent writing the application (the awarded funds are likely going to be divided by the number of researchers in the group). I have also been quite good at getting funding from other partners or private entities (only a small share from companies), so I find it hard to stay motivated for these public grants. Yet, it remains mysterious to me why other researchers in the group stay motivated -- they would be better off doing their research than writing this complex grant application for an overall small sum. I must say I have quite a bit of experience in academia, and almost always got easy funding (not public funds) in the past. It looks like some researchers enjoy "winning" a grant regardless of how small the funds are. 

Do you have thoughts on this? I feel odd that I'm not sharing their enthusiasm; and it looks like I'm missing some key element.
I'm not sure if this "answers" the question, but my belief is that people apply for grants for a combination of one of two reasons:


they want the money itself
they want the record of succeeding in getting the money.


While true of both public and private money, part of the prestige is that grants put their money where their mouths are. And public ones -- especially with longer histories can bank on those names (whether the banking is always warranted is of  course another question).

Your point is vis-a-vis 1 and could be restated as (A) more money is available through other means or (B) the amount of work vs. amount of money is a bad deal.

But the defense of pursuing famous public grants centers around 2. These public funding sources are (A) well-known, (B) perceived to have solid review processes, and (C) they are seen as prestigious because of (A) and (B), which should also make them (D) highly  competitive.

These features tend to make them attractive for career purposes. This is especially true when the quality of research is being evaluated by people who are not in the same field. I've got no idea what the Annual Peanut Factory Conference C's level is, but that the Snickers grant comes with $10,000,000 or even $1000 tells me that nut researchers would have competed to get it, and that you getting it means something.

In Japan for instance, Kakenhi from the government and how much you've gotten is a metric for getting jobs. In the USA, having gotten NSF or DOE grants can also help you in the future to get better positions or money.