Why is x86 still used?

Can you explain to me why the x86 architecture continues to be used extensively in modern computing, despite the advancements in technology and the emergence of newer, more efficient architectures? What are the key factors that have kept x86 relevant and dominant in the marketplace, even as other architectures like ARM and RISC-V gain traction? I'm particularly interested in understanding the software compatibility, ecosystem support, and economic incentives that may be driving the continued use of x86 in various applications.