Thunderbird gets $3 million and search licensing gets between $500-600 million.
Meanwhile, practically everyone claiming Mozilla should just start collecting donations seems like they are suggesting that it's a revenue panacea that can take the place of search. So that's the key difference.
Also, if you're following what I'm saying I'm other posts, you should note I explicitly said I have nothing against donations. I said they were likely to be a modest side hustle rather than a replacement.
Imagine what it's like from my perspective to go out of my way to say I have nothing against donations to have an internet rando claim I'm contradicting myself by not acknowledging their usefulness on the margins.