Black hole, an endpoint?

Answer

Many different questions, which I try to answer to a certain level one after the other.

“If a black hole is an infinitesimal point”

A black hole does have dimensions. Its radius is proportional to its mass. For the mass of the sun, that radius is 3 km, for the mass of the Earth (which is 300 000 times smaller than the sun) it is one centimeter.

“and sucks everything around,”

That is a persistent misconception. If the sun shrank into a black hole, it wouldn’t suck us in any more than it does now. It is true that you then come closer and can therefore be attracted harder. And so there will be forever.

“then eventually one black hole will suck up another black hole.”

Only matter that comes close enough to the black will fall in. But as long as matter can fall in and not get out, the tendency is indeed for the black holes to grow. Clusters of galaxies sometimes collide, and it is inevitable that the black holes at the centers of those galaxies are fed by stars and gas. The merging of those black holes themselves is also happening. So you can expect that on a very long time scale all the mass of a cluster will be united in a large black hole.

“And if there is only 1 black hole left and everything is gone,”

Clusters of galaxies are the largest bound systems in the universe. So in the limit you have a black hole for every cluster that was there. They are too far apart to all end up in the same hole.

“and this black hole can explode after a while”

It doesn’t explode. The idea is that a black hole slowly loses mass as a result of an effect that ‘Hawking radiation’ happens. That happens much slower than the formation of the black hole. The bigger the black hole, the slower it evaporates. So you speak of a time scale that is several tens of orders of magnitude longer than the universe is now old.

“then this is no longer an infinite point? because then it has an end point, because it explodes or something like that.”

So it has never been an infinite point, and has not exploded.

“If that has already happened to us so much, are there more universes?”

A universe in which all those processes take place until their consummation, is therefore a universe that has to get terribly old, and then it is simply most likely that it will always exist. So it doesn’t fit very well with a universe that preceded us.
The question of the existence of multiple universes has nothing to do with this whole argument.