VCs want you to go big or go home so they want you to hire. Hiring decreases your runway dramatically.
$100 million lasts practically forever for 2 people. $100 million lasts through most problems for 10-15 people. $100 million doesn't last very long at all for 100 people.
If you have $100m, the implication is that the VCs want to see a unicorn (>$1 billion). You will be engaging in a lot of sales, marketing and engineering activity to get there. Your activity is expensive.
And nobody is getting $100 million anymore. Good raises are now in the $10 million range and that doesn't last long at all even if you only have a small number of employees.
It’s a nice meme about Twitter being an atrocious business etc (and it wasn’t great/it was struggling for much of its existence), but Twitter made $1.2 and $1.4 billion in profit in 2018 and 2019 respectively.