Where does the energy required for excitation of electrons in hybridization come from?

We're commonly taught that when atoms want to hybridize in for instance methane, an electron is excited from $2s$ to $2p$ to allow for four unpaired electrons, which is necessary for bonding.


Where does the energy for this excitation come from?




*Ab initio* hybridisation is a concept taught in schools to help understand how carbon with its one s- and three p-orbitals can achieve a tetrahedral environment. As part of this process, it is required to *formally* excite an electron.


*Formally* is the key word here. The entire process is a *formal* process that has practically nothing to do with real-life atoms (especially because these real-life atoms rather rarely end up in a vacuum without anything around them as the theory assumes). Thus, in real life this formal energy is not needed.


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In this process the energy of s orbital increases, but the energy of three p orbitals decrease. 


This is like irl two hungry friends one of them having spam. The one with spam will share it with a friend and (if you look at him alone) his state worsens (say -1). On the other hand his friend benefits (say +2). Sharing still brings the benefit to the system.


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