When you put together very large sums of investment you don't have a 100x expectation for return. The institutionals which will take on later stages of this financing just want to outperform the other investment options they have for that amount of casH (not that many).
Your 20Bn upside for Hyperloop is very low. If done to scale and over the long haul it's a very big opportunity. Even then I know of no investors - ZERO - who wouldn't take a 20x return on a billion dollar placement.
Finally. Instagram. Really? An outlier like that is what you're going to base your idea of investment on. Look at VC returns. They take a portfolio strategy for a reason.
It's a common misunderstanding that VCs want to put small amounts of money to work for huge returns. They'd much rather put much bigger amounts of money to work. It's how they're structured. Do they want the odd moonshot Instagram in their? Sure. They'll take it. But they'd take 1billion -> 20billion over 1million -> 1billion every day.