Is it dangerous? Well, any mechanism that isn't working properly carries some risk, although it depends on the specific mechanism or part. I'd say it's relatively dangerous. Why? Because if you leave it like that for too long, it's possible that when accelerating from a standstill, if you're too heavy on the accelerator, the CV joint on the driveshaft could break, leaving you without traction on that wheel. Also, keep in mind that the broken piece of the driveshaft would continue to spin until you stopped the vehicle, scraping the undercarriage. This is in the most extreme case. In the more likely scenario, if you continue driving with the driveshaft like that for a long time, the gearbox will eventually suffer.
Try to get a rebuilt driveshaft; they're cheaper than new ones. Ask at auto parts stores; they usually have rebuilt driveshafts. You trade in your old one, and they give you a new one, already repaired and with a full warranty. They're quite reasonably priced.