Bitcoin Price = Demand / Supply
Did you just make that up? Here is the correct formula: D(q) = S(q)
To find the price, you solve for q and then evaluate D(q) or S(q).
When supply reaches zero and demand is a positive number, Bitcoin’s price is infinite.
The price when the supply is 0 is D(0). D(0) is not necessarily infinity.
Let's say there's 0.1 bitcoin on exchange. Someone bids $1M for it. That's $10M / bitcoin. If supply continues to shrink, for example, to 0.01. That's $100M / bitcoin. Infinite price is possible.