Burning tokens doesn't guarantee the value to go up, that's for sure, supply can be of one token but if it has no real value I don't see its valuation can go up (like the Aurora token, it's worth nothing despite the supply)
Yes of course it doesn't guarantee anything. If project is bad you can burn %99.99 of the tokens but rest won't worth anything.
But if a project good burning can help a lot. But i can understand the worry causing with the securities.