You don't have to do it all yourself; there are quite a few companies that will offer you trading capital and access to their infra in exchange for a 50%+ share

You don't have to do it all yourself; there are quite a few companies that will offer you trading capital and access to their infra in exchange for a 50%+ share of your profit. I myself am on a team at a smaller firm with a high degree of independence, around five years of experience in the industry. The infra (including FPGA/ASIC execution platform, microwave network etc.) is the big expense for latency. On the software side it's often easier for a single experienced C or C++ dev to write trading software with a hot loop of 2-3 micros than it is for a large team anyway, because it's harder to ensure memory allocation and layout coordination/discipline with multiple devs. The ideal however isn't to compete for those ultra low latency opportunities, it's to find a trade that nobody faster than you is doing. E.g. it's too capacity constrained or cumbersome for the large firms, or in a less developed market that they aren't yet in (e.g. somewhere like Nigeria or Indonesia, or some random blockchain), or it's so creative that nobody else has thought of it.