Well with 1000 USD i could buy 14x Accounts and 14x Mylor Crowling. Than i would be around 940$.

From the remaining $60 I could then buy cheap cards that support Mylor or are generally good. That would be another $4 worth of cards per account, which, especially with the new reward cards, would provide a well-balanced beginner deck.
A Mylor bot can easily achieve a rating of 1200+, which is 1. almost continuously about 5 DEC per battle won and 2. once you can afford the rent per account, twice as many lootchests in the Silver League. I've also seen Mylorbots with 1700+ rating, especially at the end of Seasons, but let's stick with 1200 rating.
Factor that into the equation:

Daily quest chest
2chest/account *14 accounts
End season rewards.
Silver 3 = 12 chests
12 * 14
2 chests per day * 14 accounts * 14 days
Around 560 loot chests per season

Dec drop per rank game
5 DEC *30 game per day *14accounts
(2100 dec/day)

Also if i would only stick with new accounts (and no mylor) i would come to the following numbers:
100 Bot accounts for 1000$
Average bot at around 600 Rating.
About 1 DEC per Win.

Daily quest chest
1chest/account *100 accounts
End season rewards.
Bronze 2 = 7 chests
12 * 7
1 chests per day * 100 accounts * 14 days
Around 1484 loot chests per season

Dec drop per rank game
5 DEC *30 game per day *14accounts
(3000 dec/day)

Bots are op.