Genomes are comprised of contrasting domains of euchromatin and heterochromatin and transposable elements play an important role in defining these genomic regions. Therefore, understanding the forces that control transposable element abundance can help us understand the chromatin landscape of the genome. What determines the burden of transposable elements in populations? The standard model suggests that drift plays a determining role. In small populations, mildly deleterious transposable element insertion alleles are allowed to fix, leading to increased copy number. However, it is not clear how the rate of exposure to new transposable element families, via horizontal transfer, can contribute to broader patterns of genomic TE abundance. Here, using simulation and analytical approaches, we show that when the effects of drift are weak, exposure rate to new transposable element families via horizontal transfer can be a critical determinant of genomic copy number. Since larger populations are expected to have a higher rate of exposure to rare horizontal transfer events, this leads to the counter-intuitive prediction that larger populations may carry a higher transposable element load. This work has implications for our understanding of the evolution of chromatin landscapes, genome defense by RNA silencing and recombination rates. It may also have implications for devising methods for pest control by gene drive.