I'm going to have to disagree with this statement.
"Demand" is a more complex variable than "there are 10 people out there and each one wants to buy 1-3 spider ball pythons, for a total market demand of 20 spider ball pythons".
However, it can be summarized in a very simple idea: How much money the market is willing to spend on a product.
If there is $10,000 total in the market that people are trying to spend on snakes, and only two are available, you could make the case that the value of each snake is $5,000.
However, if there are 20 snakes available, and the total amount of money that consumers are willing to spend toward snakes is still just $10,000, you will see prices per snake fall.
Prices per animal will fall with increased supply, even though demand remains constant.
The good news is that with constant demand, you get constant flow of goods and cash. This is the lifeblood of an economy, and especially a hobby based on sales.
I would agree that demand has remained constant, and even increased, in the past couple years for ball python morphs. However, supply has greatly outpaced demand. Breeding animals can have exponential increases in supply, and there is no way that any hobby can support an exponential increase in the amount of money that hobbyists in total are willing to spend, even with newcomers joining the ranks every day.