Some useful stats:
- Simulations needed for 1,000
: 17,678 simulations. (Good if you’re few gems short) - Simulations needed for 5,000 : 988,212 simulations. (You can buy top-tier gear)
- Simulations needed for 10,000 : 5,590,170 simulations. (You can buy a good hero)
- Simulations needed for 29,000 : 80,060,814 simulations. (You can buy the most expensive hero)
- Simulations needed for 100,000 : 1,767,766,953 simulations. (Enough to buy all top-tier hero + gear for one class)
- Simulations needed for 300,000 : 27,556,759,607 simulations. (Enough to buy everything top-tier. incl. heroes)
- Simulations needed for 1,000,000 : 559,016,994,375 simulations. (It’s probably cheaper to just buy gems)
- Simulations needed for 1,000,000,000 17,677,669,529,663,688,704 simulations. (Please, just no)
In-case you are wondering, it is possible to reach level 66. Actually, it’s not that bad as it seems. (Just kidding, don’t even try)
The formula to get EXP required for a certain level is:
(Math.ceil Math.exp((LEVEL_HERE - 1)/ 5) * 100) - 100
Which means in order to get level 66, you need 44,241,240 XP.
If you were to simulate until that amount, it’ll take you 7,277,684,733,409,796 simulations. Unless you are a billionaire with hundreds of supercomputers lying around, it is probably impossible. 
PS. An average “maxed-out” player is around level 40(Subscriber). Even at level 40, you only have 243,961 XP. 
EXP Formula is located here.