Gel formation via polymerization of amphiphilic macromers with a soluble central block and two insoluble but polymerizable end groups was investigated by dynamic Monte Carlo simulation. A simplified free radical polymerization of coarse-grained self-avoiding macromers was modeled on lattices. The simulation reproduced the unexpected experimental phenomenon reported in the literature that polymerization of PEO-acrylate or PEO-diacrylate macromers proceeded quite fast in water in contrast to in organic solvents. The simulation confirmed that the enhancement of local concentration of the polymerizable groups in the micellar cores was responsible for the rapid polymerization of self-assembled macromers in a selective solvent. A straightforward criterion to determine an infinite gel network in a finite modeling system with the periodic boundary was also put forward. The gelling kinetics associated with polymerization of such macromers with "double bonds" at both ends was investigated. Fast chemical gelation of concentrated macromer solutions in a selective solvent was interpreted from both the rapid polymerization and the more bridges linking micelles. Hence, this paper illustrates a strong coupling between polymerization kinetics and self-assembled structures of amphiphilic monomers.