It seems simple. You pull the arm on a slot machine and it starts to spin. Eventually, it runs out of gas and slows to a stop. If it lands on the right combination of symbols, you're a big winner!!! The problem is that's not how slot machines work.
Deep in the heart of every modern slot machine is a random number generator which is constantly cycling through millions of numbers. When you pull the arm of the one-armed bandit, or press the "spin" button, whatever number the generator happens to spit out at that exact moment is selected, and the wheels spin until they reach the predetermined output associated with that number.
To put this into plain English... there's no such thing as a "hot"or "cold" machine. If there's a one in a million chance at hitting a jackpot, it does not mean that if you spin the wheel one million times, you're guaranteed to get that jackpot. Because of the random number generator, you have the same incredibly high odds at a big jackpot each time you plunk your coin in the slot.
Machines are designed to pay out a certain percentage of the time, and the programmers will assign a certain percentage of the random numbers generated by the RNG to throw a few credits your way. No matter how long you sit at the machine, those small winning spins will slowly eat away at your initial stake, but refill it just often enough to keep you from giving up all hope at a huge payoff.
Certainly, there's a chance that you might pull the handle at the exact moment that the RNG spits out the number corresponding to that life-altering payday -- but if you walk away from the machine and the next person who sits down suddenly gets showered in a mountain of money, you can sleep easy. It wasn't "the next spin" that was the winner -- it was merely the spin at that exact moment in time.
If it's meant to be, it's meant to be... but it's a completely random event over which you have zero control. No need to lose any sleep over it.