There’s really no cap on this model as long as your supplier can handle scaling and you don’t run into shipping issues. I’ve had stores do $20k days during Black Friday back when that was all I focused on. I also did a store that did $2.5M in a year and a half and about $1M profit.
If a product hits and you scale the ads right, you can just keep pushing budget. The only real limit is how long the product lasts and how well your supplier keeps up. You can always keep testing new products or brand the winning one and turn it into a long term business.