If you’re flying a lot of miles anyway, it is worth it for the lifetime elite status. Complimentary elite status can save you a lot of money on checked bags, premium seating, and other fees.
Elite status can also give you priority assistance if something goes wrong with your trip and make your journey more comfortable.
However, if you have to pay for all of your flights, or just want to fly a million miles for bragging rights and to have low-level elite status, it is not worth it.