Do elaborate more? Were they being a disgrace by cheering or booing the riders / referee?
Then it's about time that promoters got off the high horse with the "use it or lose it" attitude, and actually got out there promoting. People (especially families) won't continue to hand over, say £60 of their hard earned £ each weekend just to keep a sport running if they're not happy about something. Most folk nowadays don't have that attitude -- it's all about getting the best value for your £, and if speedway is not providing that, they'll not turn up regardless.