Google adding "DRM" to Chromium is really bad. But the fundamental reason why that is bad cannot be addressed by telling your friends to switch to [the one non-Chromium browser].
That fundamental reason is:
90% of all Mozilla funding comes directly from Google in exchange for sending users into Google's ad surveillance machine. To the tune of $450,000,000 USD per year.
Google is the only company that can afford to build a cross-platform browser engine + browser combo, and they've been effectively affording two of them for decades.
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Mozilla can't afford to compete with Google in the browser space now, while Google is paying Mozilla more money every year than they're actually spending on Firefox.
The only way more users "switching to Firefox" can increase Mozilla's revenue is if Mozilla does more selling the eyeballs of their users than they already do. And doing that is literally the entire reason Chromium is bad in the first place.
Therefore, unless you're telling your friends to also support Mozilla financially, telling them to switch to it will just cause more eyeball selling.
Yes, a larger market share of Firefox users would be good for the health of the web. Developers would test in it more, so fewer pages would be broken.
But that does nothing to ensure that Firefox can even exist any longer. If your objective is saving the web from Google, getting your friends' eyeballs into Mozilla's eyeball-selling machine may offset some of the money that Google's massive yearly payment brings in. But it can never ever match it without becoming exactly the same problem you have with Chromium now.
In summary. "Just use Firefox" will do nothing.
"Pay for Firefox" may well do something. But you don't see Mozilla even offering that 🤷
Yes, you could donate to Mozilla. Have been able to for several decades. But have you ever? How many of the people you've told to "just use Firefox" have?
More people using Firefox does not mean more people donating to Firefox.
I think the biggest challenge in getting Firefox to fund itself has actually been the complicated combination of "non-profit foundation" and "corporation that builds software" setup they've been using.
It clearly doesn't work. Maybe separating those things would have better results.