If they keyed your daily driver it would cost the same to fix. If you have good collector car insurance, it will have less deductible than your daily driver and actually be cheaper to fix out of your pocket.
I don't see kids picking on an older car just to key it. I don't think they register much on those types of kids radar. Just as likely or more likely with a new red corvette or Porsche; which will be parked in the same lot most likely. In So Cal high profile, high end, and high attention type cars are common. People are pretty impervious around here. More likely to get keyed or stolen if you were driving a 1990 Civic Si with a fart pipe and rims.
The beach is a madhouse to park at. And tight spaces. I'd a million times be more worried about a door ding than vandalism. Same thing for daily driver. Try to park in an end spot or spot with a car on one side . Then hug the one side of the space to give you more room. Hopefully it's the passengers side you can hug, then unload passengers before you park and really hug that side.
The beach is a just a particular bad place to park. It's free, public, and crowded. It attracts people who are distracted, paying attention, teenagers, tourists, low life, etc who don't respect other people stuff. Usually it's the combination of those elements that's cause problems.