> There's no reason to assume Twitter shares can't reach the same levels ever again

but it depends on how far that "again" is.

If you bought at $33 a month ago, you'll be now getting a 60% return. You can put that in another less risky investment and still have a very healthy return over the next 5 years, say 5% , less than the historical sp500 rate, you'd get to ~$69.

So if Twitter gets back to $70 in five years Musk's offer is still an ok investment, but its growth has been almost zero for the last 8 years, it's not trivial that it would become a powerhouse in the next 5.