You can make a business that supports an open source product by providing hosting or services, but you cannot expect to be the largest provider or to make the most money off of it because you're giving away much of your labor for free.
This is all well and good if you're a company whose mission is simply to ensure that the software survives—in that case your business exists precisely to enable you to give away free labor—but we run into issues when companies want to become large and profitable and pay off investors.
That's why AWS's hosting is a problem. If you look at each database who's done it it's never about sustainability for the project, it's always that the for profit entity isn't profitable enough.