Why benzene undergoes electrophilic substitution reactions why not addition

 

Why benzene undergoes electrophilic substitution reactions why not addition?

Both benzene and alkenes are susceptible to electrophilic attack because of their exposed π
 electrons. both react with electrophiles to form stable carbonium ions. 

The carbonium ion produced from the alkene usually combines with a nucleophile to give the overall addition product.

The resonance energy of benzene would be lost. instead, the nucleophile removes a proton from the carbonium ion intermediate. the loss of proton allows the electrons from the C - H bond to go back into the ring and regenerate the automatic π system, net charges is the replacement of a hydrogen atom by an electrophile.

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