The Eagles acted swiftly in replacing the former Inter Milan and Ajax boss, giving the Dutchman his marching orders just 77 days after naming him as Sam Allardyce's successor.
De Boer arrived at Selhurst Park with a famed 'Total Football' style of play, which ultimately backfired on Palace's behalf as they struggled to get going and are still without a league point or a goal five games in - four of those under the outgoing manager.
Speaking on Holmesdale Radio, Parish said: "As a club we got it wrong and as a chairman I got it wrong with Frank. But I am never going to apologise for taking a risk and trying to improve this club. If I make mistakes in doing it, then I will hold my hands up. But I am not going to apologise.
"The road to hell is sometimes paved with good intentions. I can understand people thinking four games is not enough but results were not good. Frank was here from July 1 and in the end I did not think it was going to work. It could have gone on longer but if that then produced the outcome I thought it was going to, then that makes me negligent.
"People honestly say they want to write off the past seven years because of where we are now. I see people saying, 'it is time to go now'. It is kind of an Alan Curbishley moment if you're not careful. Am I happy with where we are now? No.
"But am I about to be thrown off course by half-truths, vitriol and people who know one per cent of the facts and are completely irrational in their criticism? Nobody likes the records but the only thing that matters is where we are at the end of the season. We have to try to get ourselves out of it."