Naturally...
Ok, let's go slowly and clear it up.
“But there were also false prophets... False prophets secretly introduce(d) destructive heresies, even denying the sovereign LORD who bought them (which) ( brought) swift destruction on themselves.”
So now, we have a clear picture of what is being said.
[2Pe 2:1 KJV] 1 But there were false prophets also among the people, even as there
shall be false teachers among you, who privily
shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction.
[2Pe 2:3 KJV] 3 And through covetousness shall
they with feigned words make merchandise of you: whose judgment now of a long time lingereth not, and their damnation slumbereth not.
The "them" pertains to the people but not to the false prophets. Do you see the "shall be" and "shall bring in"? They both are in the future tense, not in the current tense, in other words, they aren't yet among them. The "bought", however, is not stated in the future tense but could have been had the false prophets also pertained to the "bought". If you look at 2:3, you can see a distinction between the "they" (the false prophets) and the "you" (the bought). Therefore, by that, the false prophets are being differentiated, separated and distinguished, from the "bought". It goes on to discuss the judgement of the false prophets but not the judgment of the bought which would have had to be so stated if the two were of the same group, and which further reinforces that the false prophets are not part of the "bought".
Look at Mat 24:24. It is basically saying exactly the same thing as 2 Pet 2:1. It does not identify the false prophets as being of the elect (the bought) - not even close - but entirely separates and differentiates them, and again, the false prophets are in the future tense. IOW, the elect in Mat 24:24 represent the equivalent of the bought of 2 Pet 2:1 with the false prophets representing the equivalent of the false prophets of 2 Pet 2:1 with no intermingling of the two.
[Mat 24:24 KJV] 24 For there
shall arise false Christs, and false prophets, and
shall shew great signs and wonders; insomuch that,
if [it were] possible, they shall deceive the very elect.
The same with 1Jo 4:1. A distinction is being made between the "beloved" - the "bought" - and false prophets, so, the false prophets are clearly differentiated from the elect just as with the bought of 2 Pe 2:1.
[1Jo 4:1 KJV] 1
Beloved, believe not every spirit, but try the spirits whether they are of God: because many
false prophets are gone out into the world.