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 prices will go up based on demand. If people think that future of Bitcoin is good then they start buying more and more compared to sellers then its price will go higher. Currently, bitcoins are not still using in many mainstream businesses and if they start using it then we can see its prices can go even much higher compared to current prices. Don't look at its market value just accumulate in small amount whenever you see some correction to make good money in future.