The role of money in campaigns is greatly overstated in the minds of most Americans who pay attention to politics. There is a threshold, an amount of money that candidates need to raise to be competitive in a given race. Money raised beyond that amount can be spent strategically, up to a point of diminishing returns. And beyond that point, additional spending doesn't bolster the candidate's chances. A simpler way to think of it is that once a candidate has spent money on all the "right" things that a successful campaign should spend money on, all additional spending is just blown on advertising. Buying more ads is what you do when you have money and can't think of anything more productive to do with it (this is, of course, assuming that quite a bit of spending on advertising has already been done).
We saw a great example of this in 2008 when the Obama campaign had so much cash on hand that they were, in the case of swing states like Ohio, buying every single ad spot in a 30 minute program. Believe it or not, once a viewer has seen an ad a dozen times, showing them the same ad several hundred more times has no additional benefits. It's just overkill at some point.
Nonetheless, there are useful ways to spend a million dollars in any competitive race in the country right now. So it isn't entirely clear why the Democratic Party is spending that million bucks trying to help an unpopular and by any measure (other than their favorite, "she's better than a Republican") a very bad incumbent win a primary. I refer to the Rhode Island gubernatorial race, which is one of those statewide races Democrats have to go out of their way to find a way to lose.
I don't expect that party organizations maintain neutrality during primaries. Parties endorse candidates and have always done things to help those favored by the party to win. I simply do not understand why at this very moment, anyone could look at the races happening across this country and conclude that "Let's give Raimondo a million bucks to maybe fend off a primary challenger, because seriously how bad do you have to be in a deep blue state to not be able to win your primary as the incumbent governor."
Could that not be more productively spent in, say, the Florida gubernatorial race in which a competitive Democrat has the potential to break 20 consecutive years of GOP control of that office? Maybe spend that money on ground teams to pound doors, drag voters to polling places, and so on? Which does the Democratic Party have a deeper interest in: protecting an incumbent from another Democrat who very likely would hold the office anyway, or taking back something the GOP has held for two decades?
Parties as organizations make decisions that are not always outwardly logical because people in the party are not all equally influential. If you're in the clurb, the party may do things to help you even when it's not strictly rational. The favor will be expected to be repaid later. That said, it seems so clear that more benefit is derived from bolstering a race against a Republican than from trying to sway a primary where a very bad Democratic incumbent is in danger of losing because of her own actions and nothing more.