Launched in 2006 with $500 and $600 price points due to being built around an expensive blu-ray player. The PS2 was still selling extraordinarily well. Sony could have saved themselves a ton of losses if they had waited until the technology became cheaper rather than burning through all of the PS2's profit by selling the PS3 at a substantial loss.
All other reasons are understandable and correct imo, but waiting fot the technology to be cheaper? Cmon, one of the selling points of consoles is to have better hardware than competition. If they wait for tech to be cheaper, then they will lost a huge share of the market for this simple reason.
"We all make choices, but in the end, our choices make us" - Andrew Ryan, Bioshock.