I'm not sure about your calculations.
But yeah. 1 billion shares is definitly out of my reach.

And...
I do guess two things :
1 - You "probably" do use stock markets to reach amount of money you can't get naturally. Right? Meaning staying focused on the game, using the trade market every few minutes (or half hours for the higher level), and get a good trade too.... Am I right?
2 - You probably ALSO have the neon sign, that I still don't. And wasted yet again all my shares to get one more useless decorations. With my luck, I'll get it as LAST decoration. For sure.

So...
Even with that, with the lack of this neon, even if I play with trade market, I'm afraid it will take days; even weeks to reach enough level ups to get a reset worth 2 600 000 (or whatever is my next decoration price) shares anyway. Probably at the very least longer that what I need instead of doing quick runs.
I might be wrong, I might just try it anyway if you can confirm me those two above points though.

Because well. I'm getting bored. Still no neon, just don't want to do the 50+ runs to get enough for next decoration, that with my luck, WON'T be neon anyway.