What might be making you a tad apprehensive, but might not, as it's too soon to tell

[classicman]

I wasn't sure what thread to put this in, so I chose this one.
I'm about to quit my job - today is the day. Its been a total grind full of headbutting and incredibly idiotic decisions by management which I am uncomfortable with ethically and which impaired my ability to earn a reasonable living. So, I found another oppty where I am getting a much increase base and have infinitely more potential income without the layers of stupid at the old place.
I'm sad in that I really like my immediate supervisor and I'm now leaving him in the lurch.
I'm also going to miss working with one of my best friends - the guy who recommended me for the position in the first place. I'm also nervous as hell leaving a known entity for a start-up. I'm really fucked if this doesn't work out.
Dreading making the call...