Commuting - Locking up your bike question

I've learned a lot about locking up a bike but have a question about one of the methods. I've seen it where the front wheel is taken off and locked up with the rear wheel. Can't a thief just take off with your fork if they wanted to?

If they have a toolset, then yes, they can take off the stem, take the headset apart and steal your fork. They could do this even if the front wheel was still in the fork, though.

They can also steal the entire drivetrain the saddle, the handlebars, the brakes, and pretty much everything but the frame and the rims and tires, if they want to spend all evening sitting out by the bike and disassembling it.

I usually bring my front wheel in with me at work when the bike will sit unattended for 8 hours, but my MTB is kind of a beater anyways. Basically, it would cost them more to buy a new front wheel, or they'd have to steal another front wheel from somewhere else. Chances are, there are bikes nearby that they could just cut the cable and get away with a whole bike. As a general rule, the most secure bike in a given area is the one that's locked up near a high-value bike, or near a less-secure bike.

You can only do the best you can. Thieves can take whatever they want, if they really want a part(s) off your bike. Thieves prefer to take the whole bike, esp if it's an expensive one, so they can strip it at their convenience and either use or sell the parts/bike on eBay or craigslist. Otherwise, wheel-sets and rear derailleurs seem to be the most popular "must steal" items. If you have a carbon or high end suspension fork, then you have another thing to worry about and need to buy a u-lock to lock the fork and frame together.

I bring my fork inside with me.