these "price indexes" are usually a simple API call to one or a couple of exchanges to get their prices and the site lists them on the top. and because of that, crazy things like this happen.
it is always the programmer's fault for not thinking ahead about these kinds of bugs. for example a simple comparison (1 line of code) can prevent stuff like this. you fetch the price from 3 sources for example and then compare them. if the price is ridiculous in one of them (like being 200000 in one place or 100) it is obviously a mistake and you automatically ignore it and then save a bug report for the "human" to check it later.
In few years the bug will be the opposite. The '$15,000' tag will be the smallest and you'll need to correct this because BTC will be a lot higher