Well, you can:
- neither measure "speed" of development - and while there may be resistance from the developers, the most obvious "speed" measure is the "release count", as most people assume "decent" release cycles;
- nor can you directly translate "speed to money".
So while in general, money WILL benefit the project, you have essentially the same situation as in FreeBSD, Debian, or... indeed, Windows itself. (MS has no "direct magic" how to translate salaries into new qualities, either.) That is the way of every art and science.
And while I do not see ReactOS replacing Windows in large corporations anytime soon, I do see for it two niches:
1. As a "teaching system". ReactOS has become a very serious OS. And yet it allows for you to further complete elements of it. That is the stuff of master or doctor theses. It shows the involved student to be both capable of understanding one of the most mainstream OSes (Windows) AND AT THE SAME TIME participate in a sort of fringe startup (ReactOS). In order to be successful, the student shall both follow "the accepted practices" AND not "overextend his abilities". I believe this shows good personal and professional qualities, and may be a good starting point for an IT career.
2. As a "private system". Once ReactOS is useable for small everyday tasks, i.e. not running some who-knows-what server, but rather, a decent office suite, etc. - it can be used on cheap machines in the developing world (which is, in fact, a giant market). (Including small VMs on such "cheap machines".) - That would be VERY valuable for the project, but reaching THAT will make ReactOS very valuable. - The main "danger" to this is IMO, ironically, Android. (Cheap keyboardless tablets are quite enough for the tasks of most people.)
In my personal view, ReactOS "feels" like... Linux around the turn of the millennium, perhaps like just before kernel 2.4. - Linux was then in no way able to "challenge" yet the "big" Unices, but soon afterwards, it became "everybody's darling"... I think the "community edition" might be the turning point.