I was wondering this too.
Because it's all very well everyone here comforting the Op and saying people are bitter/jealous and she's totally loved by everyone except the few, but if that isn't true (and no one here can know either way) then that really isn't helping anyone.
OP:
Who told you? Why did they tell you?
How has the event been going?
Do lots of people come?
Are there lots of other volunteers?
Have numbers of attendees/volunteers dropped over the last few years?
Do others volunteer or do you have to ask? Do volunteers stay a long time, or do they drop out quickly with mutters of "being a bit busy"?
How do you feel when someone comes up and says they want to help?
But also to think about:
Do you listen to other people's idea?
How many of other people's ideas have you done? How many of your own?
Do you talk to others before doing things and get their input?
How would you react if the organising group discussed your idea and a different idea and voted against you?
Because if generally the event is going as well as it ever has, and there are similar number of volunteers and people who volunteer stay doing it, then I wouldn't think you are the problem.
If you're seeing a lack of volunteers and people coming then it could be that the event is less popular, but it could be that it has become something that's more about you than the event.
I've seen the situation where someone was accused of taking over something-they weren't, and they were very good at making everyone feel valued. However some of the people from outside saw them as a "queen bee" and assumed that they were dictating everything. In fact very few of the ideas were their own, just they were good at taking someone's idea and making it grow wings, and especially good at making sure that credit went to everyone including the quiet ones who did the boring tasks.
Equally well I know someone who if they aren't In Charge, they aren't interested. They are apparently astonished that any committee/group they join to do such things dwindles away and leaves them on their own. The only people they want round them are people who tell them what a wonderfully organising person they are that the events would never happen without.