To steal Bugatti in Bitlife, you must first age to the point where stealing cars becomes unlocked under the crime activity tab.
The option to steal cars will unlock around the age of 15 in the game, and when it unlocks, you will be able to steal cars by using the grand theft auto option.
That said, if you want to steal a Bugatti, you will need to click grand theft auto under the crime tab and then search Bugatti from the list of cars to steal.
If you don't see a Bugatti among the cars you can steal, try restarting your game or exiting the app to reset the list. But if you still don't see it after doing either, try aging up at least once.
Doing all of this should be enough to get the car to show up, in case you don't see it. But if you do see it, you can steal it by clicking on it and then pressing yes to stealing it.
Be careful though, things can go bad quickly and depending on how well you are at committing crimes, you might get caught by passersby or even the cops.
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