I think I finally understand it. If the market is random, it pays correct odds. If you are looking for an even money bet, you can find one anytime. At 50, win at 60 lose at 40 is 1:1 and that's what it pays minus the vig. At 45, whether you are long from 50 or just thinking about it, it is a 3 to 1 bet and that's what it pays. So the post which started this thread saying 50/50 is hard to find is incorrect. It is there anytime, if you believe the market is random. If you don't, excellent timing and flawless execution can tilt what many believe to be even odds in your favor.
Theoretically yes- but only if you could trade without execution costs (commission and slippage). Add those in, and the 50/50 slips to something like 48/52- like the roulette wheel in the casino, a game that can never be won over the long term. Traders wrongly see blowing up as the great fear- but blowup risk can be addressed fairly easily with proper money management. The true great annihilator is zero. The trader must figure out how to attain escape velocity and pull away from the black hole of net-net (which is actually a loss after time and energy are factored in).