If you mean by changing it, avoiding leaving the EU, that (imo) would have been disastrous, in many ways more disastrous than the consequences we are now bearing witness to. It would certainly have been even more divisive, and once the die was cast we had to (imo) see it through and deal with the consequences, which we now are.
The fact you’ve cited five PM’s in six years is quite telling, given the 37 years that preceded it, a time of pretty much constant economic growth and political stability (within the EU), had exactly the same number.
The people’s choice to which you refer has unleashed forces of chaos and uncertainty which has left us poorly equipped to deal with the challenges that the whole of the western world has faced in recent years, and will continue to do do.
The people chose, and it’s absolutely correct that choice was honoured, but don’t be surprised when people who stridently opposed it feel compelled to point out the predictions they made at the time have become reality, especially when that reality is having such a profound effect on this country and its future standing in the world.