This is true even if the selling of your holdings causes the market price to drop.
Who exactly do you think is hanging around with a half-billion in cash thinking "Gosh, Lyft would be a good buy if it were one cent lower, but it's not good enough for me to buy right now?"
If you own $1B shares of Lyft, and you think it would be great to sell them for less than X, you’d be pretty dumb for not selling whatever you can at X. The fact that they are not doing this suggests they would not be happy to sell for less than X.
These large shareholders might be quite happy to have a way out without taking further losses, even if it doesn't mean further gains.
The major shareholders of Lyft are absolutely known, and that's because federal law requires disclosure from everybody over 5%. And I promise you that people who have or who are thinking about taking a serious position in Lyft pay attention to what they're doing.
An obvious example here is Musk's shenanigans with the Twitter acquisition. He was required to declare his stake publicly, which bumped the stock price. When things weren't going his way, he threatened to dump his whole stake at once, the implication being that the stock price would drop precipitously as he burned through the order book, causing much sadness among remaining investors.
Elon musk saying he would sell his shares because he was backing out of an agreement to purchase those shares at an inflated price is obviously going to drop the price. This is not the same thing as a random shareholder who happens to own stocks and wants to divest some.
If you want to sell all your shares for X, you’d be an idiot for not selling some of them for more than X. This is not difficult to understand.
Acquisition offers for less than market value are extremely rare, absent non public information. They are called takeunders. They generally only happen when a company is on deaths door. Which lyft is not. It would be seen as really dumb to offer less than market value in an acquisition bid. Stop making up rhetoric as if this were a normal reasonable thing to do. It’s not.
Your simple-minded models work for random shareholders, but not for people who own significant fractions. They're playing a different game. They can't exit without moving the market. Their actions are tracked by other players, who will treat it as material information. Liquidity is not some magic reservoir; it's composed of individuals with fixed sums of money making trading decisions.
I will take your continued inability to name anybody who would buy a major stake in Lyft at market price as an admission that you agree there's nobody like that.
Since you claim to be concerned about straw men, I'll point out that I never suggested "this were a normal reasonable thing to do". You asked why somebody might take an offer that didn't have a premium, one that "won’t be higher than the current stock price". I explained why Lyft's current shareholders might do that. That's all.