Far too simple of an analogy. First there is competition between miners so there's never going to be a single source, plus there are millions mined already in the pool. Also, bitcoins are currently divisible to 8 decimal places but that can be changed as soon as it's needed.
It's quite possible in 20 years that 0.000000000001 of a bitcoin will make the average house payment and by then, we'll have friendly names for all the decimal places.