Perhaps another thought on this matter.

Note that Peter starts by saying that there were false prophets among the people (Israel). It seems to me that this is his "reference point" in the whole argument about the false teachers. Also note that for the rest of the chapter he uses examples from the history of Israel. Is what Peter is saying not referring to false prophets among the people of Israel after they have been redeemed (bought) from slavery in Egypt. The false teachers among the people were also redeemed from slavery and they have seen and experienced God's great deeds, but nevertheless, they denied him. Is this not what is happening in eg., Exodus 32 with regard to the golden calf? And there are other examples as well as you know.

Now, if we go to 2 Peter 2:20-22 we read the following about the false teachers:
Quote
For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning. 21 For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them. 22 But it has happened to them according to the true proverb: “A dog returns to his own vomit,” and, “a sow, having washed, to her wallowing in the mire.”
The false teachers, therefore, know the way of salvation but they deny it. It is not that they deny it out of ignorance, but they have full knowledge of the way of righteousness, just as the false prophets among Israel at the exodus knew how they were redeemed from slavery in Egypt. My suggestion therefore is that in 2 Peter 2:1 the apostle might be referring to the false teachers/prophets among the people of Israel at the exodus and use these as an example.

Johan