I offer you $150k to take anytime within the next few months. You can take them now...or wait and see if you get a better deal in a few weeks. The $150k is still here. For you, if you need it.
What better deal? This turns into an extra $150k of investment in any future deal you get.
If someone takes this and then Sequoia knocks on their door the next day offering them $20M at a $100M valuation, the fact that they took this deal just means that they get $20M+$150k at a $100M valuation.
I offer you $150k to take anytime within the next few months. You can take them now...or wait and see if you get a better deal in a few weeks. The $150k is still here. For you, if you need it.
Just don't rush is all I'm saying.