Check the Lancaster House speech where she set the most extreme conditions for departure I.e. Leaving the single market and customs union and the ECJ. Prior to this speech, there was no fixed idea about what the referendum meant in practice. After her speech there was no way back.
https://ukandeu.ac.uk/the-facts/what-is-the-lancaster-house-speech/
60,000 is way to many. They need to be able to fit on a giga yacht.