No, they absolutely do not. Pulumi - as in the actual tool, not its developers' equivalent to Terraform Cloud - would still exist and would have used those providers regardless of whether or not there's some Pulumi equivalent to Terraform Cloud. Pulumi also would've existed (and resulted in indirect profits via Pulumi Cloud) had that provider ecosystem not yet existed; it just would've been Pulumi starting it instead of Hashicorp/Terraform.
> The providers determine whether I can even use the tool to do what I want in the first place. The providers are 99% of the value!
And you can use 100% of that value without paying a fraction of a penny to Pulumi, just as you can without paying a fraction of a penny to Hashicorp. It's a completely different offering from their respective paid products altogether.
> I absolutely believe they indirectly profit off of that.
You say this as if it's a one-way street, but it ain't. Pulumi and Hashicorp profit from there being an ecosystem of providers compatible with both and therefore useful to both sets of customers. That's one of the main sales pitches for open source, after all: to collaborate on something that benefits everyone instead of wasting a bunch of effort on independent silos.
That is: Hashicorp indirectly profits off Pulumi's own contributions to that same ecosystem. They could profit even more by making Terraform compatible with Pulumi's provider interface (even still! I'm pretty sure Apache 2.0 code can be included in non-FOSS codebases, BUSL included).
Like, the relationship between Hashicorp and Pulumi is not just to the letter but to the spirit of free and open source software. If Pulumi's existence and success (despite being nowhere near that of Terraform, and despite also being open source - even more permissively so, in fact) is indeed what motivated Hashicorp to switch Terraform from MPL 2.0 to BUSL, then that's toxic as all hell and completely nullifies any of Hashicorp's lip service to "open source".