Sefer Likutei Yehuda quotes the following idea in the name of his grandfather, the Chidushei Harim zy”a:
The Mishnah (Pesachim 99B) says that even a poor person should not drink less than four cups of wine. This is because Chazal say (Bereishis Rabbah 8:4) that the four cups represent the four words used for the geulah: “V’hotzeisi, v’hitzalti, v’goalti, v’lakachti (I will take you out, I will save you, I will redeem you and I will take you to Me).” The Sefas Emes (Va’eirah 5647) writes that the four terms used for geulah symbolize the four worlds of “Asiya, yetzirah, beriah and atzilus.”
Thus, the Gemara is saying that even a poor man – meaning a man of lowly spirit – should not have less than four cups. This means that even such a person has a share in every world.
