The other big one is that deflation likely encourages hoarding at the expense of consumption, so as a businessman, you should also expect very few customers.
This is false. Deflation does not encourage hoarding. The argument that deflation encourages hoarding works just as well to argue the deflation encourages spending.
Say I hold some asset that's going to go up in value. The fact that the asset is going to go up in value means that the asset includes the right to hold that asset as it goes up in value. The more the asset is going to go up, the more the right to hold the asset as it goes up is worth today. So deflation encourages spending by increasing the present value of an asset, meaning that you can get more goods for it today than you could otherwise.
This is, of course, an invalid argument. But it's invalid for the same reason the argument that deflation will encourage hoarding is invalid. An asset that will be worth more in the future will be worth more today because the price today includes the present value of its expected future prices. Everyone who owns a bitcoin today also owns the right to have one bitcoin in five years. If we all agree a bitcoin will be worth X in 5 years, a bitcoin will never be worth than the present value of X in 5 years.