Re: What is the combined net worth of all bitcoins in existence?
if you mean Bitcoin market cap right it's near the ~$70,000,000,000 but it's only relative to the unit bitcoin price, which can change the market cap drastically with a small unit change 
Since the net worth of Bitcoins is that high, I don't understand how prices are still rising so rapidly.
The answer is quite simple one, the Bitcoin user base is around 15-17 million users, the Bitcoin still is in its early stage of adoption, more people are coming in for this revolutionary technology thanks to recent media hype and good news surrounding bitcoin, like japan accepting bitcoin, the south Korea news and so on. The end result is everyone wants the piece of the pie, but there isn't much supply to meet that demand, causing a surge in the price, just imagine if the Bitcoin gets around 100-500 million users. There is much to come, this is just a glimpse.