Electric railing gates with spikes, security lights and many locks.
Possibly makes it more attractive to the professional thieves. More obviously something to nick.
Anyway, was in a shed/garage I take it. Don’t have to answer that, but bike thieves are more comfortable with such targets as it’s not breaking & entering a residential property. Less risk of coming across people and far less of a crime to the police so even if caught it’s barely a slap on the wrist compared to breaking into a house.
If determined enough though they’ll find a way.
Oh, and most probably know this already, but worth saying again that Strava is actively used to target bikes. Use privacy zones around the house if you ride from home and set them in various spots near the house overlapping, not centred on the house as you can work out the centre of a zone. Also, don’t put the names of your bikes in your bike profile. Easy to search for expensive bikes, see where they are ridden, sit in a car park waiting for them to be loaded or unloaded and nick them while not looking, or follow home. Same goes for bike photos attached to rides. Use enhanced privacy, careful about who you let follow, don’t join Strava clubs. Even then, anything on a leaderboard can be viewed even with privacy on.
Or just don’t use Strava 😉