What are the odds of tossing a head on a coin with a head on both sides:
Very nearly 1.
The fact that is isn't a fair coin is a new piece of information that needs to be taken into account when calculating the odds.
If I hold a confirmed lottery ticket matching the winning numbers then the odds that I HAVE won are very nearly 1. I have a new piece of information upon which to recalculate the odds.
Before the draw I all I know is that there are 146 million possible outcomes and I only have one random one of those. On that basis I calculate my odds.
After the draw there is only ONE possible outcome and I know that I have that on my ticket. Now I calculate my odds again.