I hate this question so much. I wish it was illegal to ask. You have to give some vague bullshit or you might tick the interviewer off. They know your answer will be bullshit but will ask anyways. And then every now and again you get some lumpen bootlicker asshole who refuses to abide by the social contract and wants to know exactly why you are seeking a new job and won’t accept the customary bullshit answer.

“Pursuit of new experiences and skills”, no matter how much the actual answer is “Because the only way to even make CLOSE to what I’m worth is to leave every firm I’m employed by within three years of putting boots on the ground, and to negotiate up with each new firm. Fuck loyalty, you’ll have none for me, you’ll be LUCKY to get a two-week’s-notice out of me.”