The single word that matters most I think to keep the company productive as it grows is alignment.
In addition to relentlessly resourceful, you want a tough and a calm cofounder.
M&A negotiations feel really fun. This is one of the biggest killers of companies, is they entertain acquisition conversations.
You have to be intense. This only comes from the CEO, this only comes from the founders.
You want to continue to be run by great products, not process for it's own sake.
AirBnB happened because Brian Chesky couldn't pay his rent, but did have some space.