Lots of mention of cellular, cellular hotspots and even satellite as an alternative to campground Wifi. They are, but they also have their limitations if you want/need a high speed connection all the time. Many cellular plans include a 5GB/month limit and overage charges can be pretty steep. A single movie can be as large as 2GB. Depending on where you travel, there are still a lot of areas where cellular service is not all that great. In the past year of travelling through the Southeast and Southwest, it has been rare to get 3G speeds over 1.5MBs and there are lots of places that still have only 1X service. 4G is growing, but it is not everywhere. Cellular systems are not immune to overloading either. Don't expect high speeds at places like Quartzsite or Sturgis during peak season.
Basic satellite service is not all that fast and I am not sure if they still limit bandwidth during peak hours and slow the speed if you exceed it.
In my experience; the only way to get consistent, dependable high speed internet is with a wired connection (phone or cable) which is available at many RV parks if you will be staying long enough.