I believe the odds are calculated against the number of possible numerical combinations, not the number of tickets sold.It seems like the odds would be more favorable when the amount is smaller, with so many saying they only buy when the prize is high.
Now the odds of being the sole winner would be MUCH higher right after someone wins and the jackpot resets.
Id be perfectly ok if I won it alongside 19 other people, hahaha. That is still around $20mm after lump sum and taxes.