I have found that if you teach in a creative manner, you are well able to cater for the advanced and the beginner player in a group.
Here's a little tip: Make sure you give everyone some headphones too. You can then make the beginner practice a riff/lick while you help the more advanced student out.
Groups are harder to manage, but true if you have 10 guys paying $35 that is $350 for the hour, so potentially lucrative.
JUST make sure you always give top quality instruction and lots of value!