I started with very little at a time when CL wasn't released and Untamed was sold out.
There weren't even pack drops in chests.
The only way to upgrade was to buy individual cards on the secondary market.
I am now lucky enough to have enough CP for Gold II, but I had to invest.
I've experienced the tiddler and minnow side of the game, but doubt I will ever be a whale - although it won't stop me from trying.
10,000 packs is around $40,000 on the primary market for Chaos Legion packs and then there are the vouchers required for the additional free packs and the potions would be 5 per pack. So 50,000 of each potion for higher Legendary and Gold Foil drop rate.
That's a big investment, more than just a grand or two.
If you want to run 50-100 guilds, say 10 accounts per guild, that's 500 accounts minimum, to divide the 50,000 cards into.
Then there is the cost of setting up so many accounts at $10 each for the spellbook, or buying them from other botters who'll sell for $1 - $2. Then there is the risk that the sellers can recover their accounts within the first month or so after the accounts are transferred and you change the private keys changed.
I wish you luck in your venture.
Unfortunately I don't have the capital to make such a large investment, and there are some risks.