You are right, I haven't seen that before. Is there any explanation how much must be bet to have access to more than 1 exchange?
For now I think each time I roll RP from daily WOF I will exchange it back to WOF.
I bet a little daily althought I'm far from being an heavy better and it says I could exchange 39 WOF tickets per day.
I'd say to you, try to bet a little, even very little, for a week or two and see how it goes.
As long as you are betting at a level that is good for you, do not worry about how much you are betting. There could be some rewards, there could be competitions, there could be promotions, there could be anything but as long as you are within your financial possibility levels, that will be fine and you should not worry about it.
I personally do not feel any pressure at all about the fact that I have some small tiny amount to gamble. I usually gamble with 100 satoshi each on my bets, it is tiny compared to everyone else and yet I am having a lot of fun with it. Maybe I won't get rich, nor will I become huge name here and win big things, but I am happy.