why some altcoins must burn.?

[fileo]

Basically projects have been developed with own unique coins.
But why need to burn coins if it was not created to burn.?

[blue_id69]

The coin need to burn to decrease the supply, if there an ICO with 20m total coin supply but only can sell 15m while ICO, the unsold coin or token must be burn to prevent dev dumping it on open market. And the price will be higher cause the supply decrease right ?

[Red-Apple]

by "must burn" do you mean as in the shitcoins should drop and burn to the ground and disappear because they are useless projects.

or by any chance you mean when the developer for example burst the coins? this is called "Proof of Burn".
in which case there is no must burn in most cases. they choose to burn some coins in a certain way for different purposes.
read these two links for more information:
https://bitcoin.stackexchange.com/questions/50525/how-does-proof-of-burn-work
https://en.bitcoin.it/wiki/Proof_of_burn

[Entei]

There are several situations, in currencies normally the team and Dev create a system in their project, with quality margin, profit margin, margin of Marketing, and even where your project may arrive, when some of these areas is affected along with your main goal the team asks their investors one opinion about burning through searchs or even freezing. In the case of Tokens occur this process due to expected non-sale, the burning is one of the means to increase scarcity and attract possible investors.

[loaddebitcard]

Because there are too much of them. More than 90% of all coins are crap. There are only about 20 altcoins that are real cryptocurrencies. Others are useless rubbish. ICOs should have new model of token distribution. Tokens should not be equal to coins. Tokens need to be different kind of asset.

[cryptogeek101]

I think you burn altcoins to increase the value of the remaining coin in circulation. This is because most cryptocurrencies have finite total number. The decrease in supply will cause the price to go up.

[shandi albert]

Many Ico are burning coins when the sale of coins is not up to the hardcup so that the future coins can be stable and the price is not too cheap, Coin supply is slightly more expensive, because of its scarcity.