Not true!
Might have been the case last time you looked at a science book/paper, but science moves on inexorably, keep up!
https://www.newscientist.com/article/mg23130870-200-life-evolves-so-easily-that-it-started-not-once-but-many-times/What scientists do say is the life we see around us now comes from one point source (the last universal common ancestor, LUCA), the DNA in all living things being related. Even this is not as straight forward as it seems as certain cell structures including mitochondria, chloroplasts, even the nucleus of eukaryote cells are the result of endosymbiosis, where cells of one type co-opt bacteria/archaea/viruses in a mutually beneficial way.
However, far from being a difficult miracle, scientists (Thomas Carell, Michael Yarus etc), taking a methodical approach have found that the basics of replication (RNA, coenzymes) can be reproduced not only in the lab but in a variety of conditions (frozen, dry & in solution) using naturally (to the times) occurring chemicals (hydrogen cyanide, ammonia, formic acid), add clay which carries a natural electrical charge that pulls in the RNA to form long chains and off you go.
These studies show the possibility that these building blocks would appear repeatedly in a wide variety of situations, that we have only one of these start-ups left as the source means, not that the others never happened but that once the more complex LUCA got its break, it out competed, ate/absorbed the others probably in an extinction event of huge proportions.
Now this is all speculation as it happened billions of years ago, but the ease of spontaneous reproductions of the basics of life, in all manner of niches does show that simple life should be ubiquitous, whether that leads to intelligence is another matter.
Personally, I think it probably sometimes does, but the jump to galaxy spanning civilisations is huge, the distances alone make the mind spasm. But we only have to look at ourselves to see the main problem, the amount of times civilisation has risen and died before we got to where we are now. The Mayans, the Anasazi, Easter island etc. as Jared Diamond outlined in his excellent book “collapse” environmental change and decisions of mind numbing stupidity, such as, chopping down the last trees on Easter island to transport the huge stone heads that must have seemed so important at the time, our current crop of climate change deniers should read that book.
Our short termism and unwillingness to learn from the past, coupled with an (up to now) largely benign universe has let us reach the edge of two things. The possibility of spreading out into the solar system and total collapse. The latter is what I think happens to those that reach this stage.
Evolution provides a set of behaviours to go with intelligence, that include aggression, to conquer predators and others like us, over-use of materials to out compete and the ability to credit our success to our own brilliance and extrapolate from that that this will continue forever. These traits, like evolution itself are likely to be universal, it is likely that the peaceful, wise races that Captain Kirk and others like him meet in fantasy land were chopped to bloody pieces before they got a look in, but even if they weren’t, we have been incredibly lucky.
Our sun doesn’t bathe us in deadly burst of radiation like many would, we are away from any concentrations of late stage red giants that explode into supernovas scouring us from existence, we haven’t been whacked by any large rocks lately.
I think life largely hangs on in the face of its own failings, succumbing to either that or the capriciousness of an uncaring universe, that rock is coming, enjoy!