Isn't this the case everywhere? Be it Indian political parties or African countries or even the local club. I mean, if you want to introduce democracy (by which process you are giving away something), you should be convinced that the opponent plays by the rules. However, in most cases, it is tough to find an opponent who is guaranteed to play by the rules. However, if democracy is introduced and works successfully for a few years without anyone trying to misuse it , in that case, it will stay for good.
One implication is that you try to introduce democracy when you know that you will win the first round. Given that you want to introduce democracy means that you aren't THAT power-hungry and are willing to give away a bit in order to secure long-term systemic gains. Which means that you are likely to play by the rules in your term as power. And once you can ensure that, democracy is likely to get embedded in the system, after which even if you lose one, you know that your opponent won't be able to do much to blindly hang on to power.
When countries become self-governing after an independence-struggle, the party that is in charge will usually be the one that has led the struggle. And it is usually confident that it can win the first couple of rounds. Hence, most countries that became independent in the 40s to 60s started off as being democracies (that many of their systems have broken down is another story) - it was useful to gain brownie points with the US, UK , etc. and there wasn't much threat to capture of power.
However, when you have got power through other means - say by some kind of an inorganic process, then there is no guarantee that you will win the first round, or second round, or ever. Hence, you have some countries that came out of the Eastern Bloc and Central Asian countries that have never made an attempt at democracy. The people in power know that once they try to bring in democracy, their power is effectively over.
On a similar note, countries that have moved away from democracy (Zimbabwe immediately springs to mind) have no incentive to bring it back - again the first round victory is not guaranteed. Yes - there have been efforts such as those in Pakistan to reintroduce democracy, but it's being done under some kind of special circumstances - such as Musharraf's party not being allowed to contest, etc. Also it has been done under considerable supervision of the US, so self-interests of Musharraf can't be so blatant.