A brief explanation why
Designed in the 1970s by electrical engineer Chuck Peddle and his team for MOS Technology, the 8-bit MOS 6502 ran at 1-2 MHz and packed 3,510 transistors. As the most affordable chip of its kind, it initially cost less than a sixth of the alternatives offered by Motorola and Intel.
The team that designed the MOS 6502 had previously worked at Motorola on the Motorola 6800 project, so the 6502 is considered a simplified, faster and less expensive version of that design.
To put that in better context, the MOS 6502 was selling for approximately $25 per chip, while Intel's 8080 and Motorola's 6800 were both selling for around $200.
By the 1980s, variants of the MOS 6502 were powering several consoles and computers like the Atari 2600, Apple II, Commodore PET, and of course, the Nintendo Entertainment System (NES).
The original NES was powered by a custom MOS 6502, which was sold as the Ricoh 2A03 and manufactured by Japanese imaging and electronics company Ricoh, who got its start in optical equipment back in the 1930s and helped popularize cameras with its Ricohflex III in 1950. The Ricoh chip also included a 5-voice Programmable Sound Generator, plus other I/O interfaces.