"Lucked into" is an idiom that means to have stumbled upon something or to have gained something unexpectedly. Some synonyms for this phrase include happened upon, chanced upon, stumbled upon, discovered by chance, or fell into. These phrases all imply a sense of fortune or luck in coming across something by chance. Other alternatives include "got lucky" or "hit the jackpot", which convey a similar meaning of unexpectedly finding success or fortune. It's important to note that while these phrases may be interchangeable in some contexts, they do have slightly different connotations depending on the situation and the tone of the speaker.