I dont doubt for a second there are plenty of people who lie about it. Its the sort of thing i expect people to make up.
But I'd be curious what the actual numbers are around that.. cause at ~1% of people alive today (and 0.25% of people alive at the time) thats a pretty massive section of the population.
I never met a single person who had claimed to go to Woodstock, so my personal experience differs, but thats another matter.