Because I'm sure we're all aware that due to the nature of random number generators, and implementations, the more widespread the adoption of Bitcoin, the more likely it is that we will see key collisions.
Are we even sure that ECDSA even has an unbiased distribution?
True, one should always speak in relative terms. You have as many chances of having a collision as you have chances of being killed by a 22-carat pure gold meteorite at the time you generate your key.