Why did so few Saiyans survive?

Our Earth's population is somewhere in the neighborhood of 7 billion. I'll estimate that Dragonball Earth's population is maybe at 4 or so billion.

While humans are a somewhat violent and competitive species, it's nothing compared to the saiyans. They live to fight, the stronger the opponent, the better. Given that, I think it's safe to say there aren't anywhere near the same amount of saiyans as there are humans. I'll be generous and say there's about a million or so, though I think the number if closer to a few hundred thousand.

Having said that, Freeza is the one deploying saiyans to various parts of the universe, so he would likely know where each of them was, if he chose to look. Even with deployments, I'd say there was still a large portion of the saiyan population of Planet Vegeta at any given time, between those too old or young to fight, plus ones to keep the infrastructure up. Taking out the homeworld would leave the saiyans with an utterly devastated population, possibly less than what would be necessary to establish a viable breeding pool. And since Freeza would know where just about any saiyan went at any given time, and the fact that Freeza probably has a decent amount of warriors at his disposal more powerful than the average saiyan (Vegeta being an outlier), it's a simple matter to hunt down most of them. Dodoria alone destroyed Bardock's group and nearly killed Bardock himself, so just send him and a few warriors of similar power out to mop up.

Freeza could increase his chances of getting most saiyans by issuing an order recalling all saiyans to Vegeta. Less mopping up he has to worry about, and he can keep a closer eye on Vegeta, Nappa, and Raditz.

There is a good chance the Saiyans weren't a big population. There was point when Vegeta said he didn't understand humans sentimentality on killing and said Saiyans killed people they didn't like as simple as that. They love to fight and battle and lack sentimentality it wouldn't be surprising if their population never grew to big as big as Earth's. That is assuming Vegeta is as big as Earth and has as many resources for billions of people to survive on it. Since the Saiyans migrated to another planet to make their new home seems to be officially canon with Super there a good chance that when Salad was destroyed that the Saiyans numbers were reduced greatly and the ones that took Planet Plant were only in the thousands. Depending on how long they worked under Freeza they may have gotten the population into the hundred thousands, since Freeza provided them with more opponents that distracted them from killing each other and allow their numbers to build.

I can see why Freeza destroying the planet left so few survivors. The whole organization forgot about Kakarot and his mission so there is always a chance there were more than four survivors. I never found the story of a new Saiyan survivor to be far fetched for that simple reason.

I agree with Salagir in that Saiyans probably were not very populous. They don't seem particularly fertile, and don't seem to breed as often as humans, and they don't really seem to like to be crowded. So honestly they could have a population in the Hundreds of Thousands or Low Millions.

And as I stated in my space baby discussion thread I get the feeling most Saiyans sent offworld actually don't succeed and are expected not to survive. These are the unwanted babies, and this may actually be a method of population control, and they are the weakest babies.

But yes I feel likely there would be several Saiyans who survived Offworld. It was also said Frieza destroyed Vegeta while virtually all Saiyans were accounted for on the planet. So it really sounds like the Saiyan population is more like a small cities worth, and perhaps that means much of the planet in uninhabitable.

Wow, I was being incredibly generous. Without outside intervention, the saiyans would definitely have destroyed themselves.

This topic brings up another interesting fact reminds me of U13 Kakarot. If the Saiyans sent low levels to weak planets to eradicate life on the planets and they got lost in paper work like Goku did (before the retcon) does that mean there were Saiyan survivors who did carry out their mission, killed all native life, than spent the rest of their lives living in isolation just waiting for when they will be picked up by their people or Freeza? 

I'm actually imagining some alternate DB universe now where the surviving citizens of Earth, assuming Roshi somehow gets killed early on, desperately searches for King Piccolo and release him to save them from the Saiyan menace, preferring his iron fist to Kakarot's wholesale slaughter.

Because most of them were on a planet when it exploded. Most biological entities tend to die when that happens. SCIENCE!  The ones that weren't and known to be off planet were accounted for by Dodoria and friends.

Well their low numbers are explained due to their excessively aggressive nature but due to said nature reinforcing their fortitude and then some, that nothing short short of an instant planet wide cataclysm would wipe them out.
Also I guess the Saiyan of Legend could rock up and fuck all the arse, leaving itself with no way to procreate.


Off topic: But isn't Betty a woman's name?

The reason is stated on page 428. "No killing while in recess, kids"