The gemara (Menachos 65) writes that there was a machlokes between the Baysusim and Chachaim on what seems to be a technical point of law with respect to the korban tamid. The Baysusim held that anyone who wanted to could donate the korban to the mikdash and it would be offered on behalf of the community. The Chachamim held that the korban must be bought only with public communal funds.
The fact that the day the Chachamim won the debate became a Yom Tov tells us that we are dealing with more than a technicality. Rav Kook, the Shem m'Shmuel, others explain that there was something fundamental at the heart of the dispute. The Baysusim saw Klal Yisrael as no more than a collection of individuals. The nation is like a big partnership between all its members (see Rashi/Ramban at the beginning of Vayikra). When you have a partnership and one partner wants to contribute more, kol hakavod -- why not let him/her? The Chachamim, however, held that Klal Yisrael is more than a partnership. The whole is far greater than the sum of its parts. The concept of tzibur is a new entity, distinct from its individual members. Therefore, the korban tamid can only come from communal funds. The funds of any individual member of the whole is not the same as funds of the entity called tzibur.
"V'ahavta l'rei'acha" means that there is a you and there is a me that are distinct entities, but we have to play nice together and work to get along. "Es ha'keves ha'echad...," the concept of korban tzibur, tells us that there is something greater than that -- there is a concept of tzibur. A tzibur means there is no longer a you and a me -- there is instead one united whole. We have to get along and because you and I are part of one and the same body, part of one and the same unit -- if I hurt you, are am hurting myself.
The rasha asks, "Mah ha'avodah ha'zos lachem?" He understands that if you do a mitzvah, G-d gives you points and all is good; if you do an aveira, the opposite happens. He understands "mah ha'avodah... lecha," what your benefit is from doing pesach. What he doesn't get is the "lachem" -- plural. How does your pesach, your seder, benefit everyone else? What's in it for them? What the rasha doesn't understand is the concept of tzibur.