Been thinking about a comment on this but it's difficult to post without sounding like I know it all.
I certainly don't and can only offer my own experiences so here goes.
I've had a number of years with trackdays, about 20 years on many different bikes and many different circuits, Spain, Portugal, France, and the UK. I have had good and bad experiences on all of them. As in life, you always come across folk that you just think are wankers, and they generally are. The trick is not to allow them to spoil your own enjoyment.
Testosterone is rife on trackdays, coping with it the key to a successful day/trip.
The majority of folk are great and in general terms the wankers soon get the message, crash or just piss off home early as they discover their true place in life.
I've had the best times of my life with mates on a group jolly which has included three days in the Spanish sun on a GP circuit, followed by beer and tears of joy, priceless.
It's good to go with folk that have experience in them, it allows you to concentrate on enjoying yourself without constantly asking questions to youself due to the lack of your own knowledge on proceedings.
I'm still a member on a Trackday forum with many racers and hard core track-dayers spending a fucking fortune on their pursuit for pleasure and bragging rights. Many of them find out the hard way before turning into a sensible rider in pursuit of pleasure rather than outright speed and lap times.
I've embarrassed a few and been embarrassed myself, that's just the way it is, there will always be someone better than you and you will never be the same on any two days or any circuit, sometimes you gel with it, other times you don't.
I've dabbled in a bit of club racing over the last three years on the efe, never expected to win anything, was just out for the fun. A 5th and a 6th in the wet was enough for my ego at this age, the self achievement was immense after building it.
Racing is expensive regardless of level and as already been said, you have to immerse yourself into it, because the race weekend itself is only the tip of the iceberg, the effort leading up to the weekend is where the time and effort goes.
If you don't want to smash it up don't use it on track, the potential is always there, it may not be you it may be the nutter behind you with his eyes on stalks who ends your day and your bike, so be prepared for it and hope it never happens.
Having said all of that, classic Trackdays/Bike events are nothing like full on trackdays, I would say there is a little more respect for each other given the machinery around, as not many of them could be easily replaced if trashed, plus the age of the donkey on top is generally higher making them a little easier going, that doesn't mean slow, that means more room when passing with no paint changing hands!
Don't worry about being scared, it's good to be scared, it heightens the senses making you more aware of your surroundings which is a good thing for trackdays.
If you've always wanted to do it, then do it, it can and will probably be the best thing you do all year, and can be very addictive so expect to have the desire to sell the kids and look around to improve your chances.
On the down side, I have lost mates in racing, seen some horrific crashes causing life changing injuries, those kind of things were always with me as I sat on the grid, that lost me a place or two I'm sure, as I had to drive the van home towing a caravan with all the gear after the weekend, so self preservation is high on my list, at the expense of some fun or bravado.
I hope to do this weekend myself, I don't care what group I end up in as I can hold my own generally, the important thing for me, is to enjoy myself in the company of mates and bikes.