Cool, the game just keeps getting more and more accessible as you keep playing it. First it seems that beating it all in one run is impossible, then it seems that getting to hell is impossible, then it seems like beating the game in 8 mins is impossible. But it all becomes more and more attainable as you keep playing, it's really cool.
500,000 gold was hard for me when I got it, but looking back it is really not difficult at all once you start doing high score runs. Properly placed vaults (ghosted) and a good amount of bombs and you can have $500k by the time you complete the ice levels. Speedlunky does take a lot of work. My biggest problem was that I was going TOO fast and dying early when I didn't even need to. When going for that, I'd recommend going as fast as you can WHILE your main focus is to stay alive. See if you can beat it in 12 mins, 10 mins, etc. Doing it that way, 8 mins will feel far more accessible. If you just rush and rush and rush you'll die a million times, not realizing that you're basically on pace for a 6 minute run.