You're not the only one that thinks that way so I'll break it down for you, its quite simple. For a 12 word seed, there are 2049 possible english words. With the English words, there are 2049^12 possible combination of seeds. Assuming I can bruteforce seeds at 1 million seeds per second, I can run through 3.1536x10^13 seeds per year. I'll be able to run through the possible seeds in 1.7365884x10^26 years. In comparison, we have 7.5 x 10^18 grains of sand on earth.
Hey, i just remembered your calculations and was wondering about one thing.
Technically even if you can run through 3.1536x10^13 seeds per year, if you consider that there may be around 10 milion of electrum wallets set-up with different seed phrases it only makes it 3153600 seed phrases to go through to find at least one working wallet.
1.7365884x10^19 years. In other words not 3000000000000000000000000 times the age of the earth, but rather