As a core contributor, Matt has expressed on many occasions he would like to be able to pay us for all the time we've spent on the project, but I've always told him we're doing it as volunteers and not for money (my day job pays me sufficiently) and I think he needs it more since he doesn't have other sources of income. And if he did get enough from sponsorships to pay a second salary, I think he should hire someone not already a volunteer to broaden the skillset of the team. One of our biggest problems at this stage is that the members of the core team don't have expertise in a few specific areas that Caddy is lacking in (e.g. metrics/prometheus stuff)
My comment was not an attack on Matt, but against the idea of forcing[1] users to pay for (/donate to) in order to use libre software. Organic donations and sponsorships are great!
1. This may have been a misread on my part, on second read, gp's comment says nothing about mandatory payment. The reason I'm wary of mandatory payments is that you'd have to quantify who deserves what, and expend more time on the administration - likey setting up a foundation or company, or which not every F/OSS project needs. Again, I'm speaking generally - a Caddy Foundation, or Caddy Inc. may be appropriate. "Open source project" is a very broad term, ranging in size from leftpad to the Linux kernel, and the needs will be different for each.