The others think the exact opposite.

We've seen as long ago as 1945 what happens when two small chunks of stuff are slammed together (the A bomb) so it's quite logical to speculate (?) that :-

1/ somehow some bigger chunks were slammed together.

2/ the big bang was just one of many

3/ enormous amounts of matter had been accumulated in an enormous Black Hole and the pressure produced so much heat it exploded

4/ such happenings have occurred many times over trillions upon trillions of years

5/ the Universe as we know it is just that, = only the bit we know about.