It's a very common mistake that smaller channels make-and it's the equivalent of graduating from college and immediately going for the top job the pays the highest. Imagine what would happen if you applied to be the CEO of Apple, Google or some other Fortune 500 company with no job experience. The same goes for collaborations. You need a proven track record of successful collaborations before someone will work with you and if you get lucky enough to work with a large channel and botch it up, chances are you'll be blacklisted among their circle of friends. If you impress, then their friends will take notice and it will open up doors for you-but you can't expect to jump to the top right away.
Ask yourself what you bring to the table in a collaboration. My channel doesn't just represent subscribers-we have access to certain food items that are nearly impossible to get in this country and our concepts push the boundaries of acceptability, so that gets us collaborations that we normally wouldn't deserve. I recently did a collaboration with a channel that had 30k subs. I'm 5x larger in subscribers, but he had 1 million instagram followers, so I stood to gain much more than he did and I went out of my way to make the collab happen.
At Vidcon, all the channels larger than mine that agreed to a collaboration showed up on time and everything went smoothly. All the channels smaller than mine that had a collab scheduled didn't show up and tried to reschedule after the fact-and then missed the rescheduled time. The lack of professionalism really shows. When the next convention rolls around, I will be much less likely to schedule a collaboration with a smaller channel. I still want to work with them, but it will be more of a spur of the moment collab instead of something that is planned out. I wasted too much time at Vidcon waiting around and trying to accommodate smaller channels that didn't bother showing up.