samdz
I was a core team member and the best in a big-corporate when they decided to start off a new product. I too "strongly" questioned their plans - and had also backed that up with presentations, projections (and better EXCEL skills). They did not have a answers to my questions and said "Trust us, it will work". Slowly I got sidelined and one day "declared" as a pessimist in the project and that it was good to have my inputs. "Wow". It was just a nice way of saying STFU. 4 years later - my projections proved to be right, and the product is in a worse state than I had expected. But they still pump in money and sales is slowing moving it towards breakeven.
$70K and at 25 with no family, you have a decent runway - but not the most comfortable. If you try to be a minimalist and use it wisely (which is hard at 25), this will work out to be enough to startup.
However, before you do your startup - you need to mature a bit more about life and people in general. Life doesn't end at 29-30. $150k p.a. is not bad. Its okay to be ambitious, but learn to be grateful and respect yourself for what you have achieved. Those qualities will be required in a long journey of entrepreneurship. And you also have couple of years to allow yourself to fail, learn from it and start again.