Because it's an intentionally obtuse Ponzi scheme. You can stake Terra on Anchor protocol which was advertised as up to 20% yoy return for lending your Terra. This creates demand for Terra, which in turn creates demand for Luna, as you can only mint new Terra by burning Luna. As long as there are newcomers buying into the ecosystem, Luna will increase in value.

Luna gets the returns from the assets the 'real money' was invested in. Terra doesn't.

The people using Terra give up their returns to Luna holders for the convenience of a universally acceptable exchange medium that is pegged to something else of value that isn't universally acceptable.

As with all leveraged investments to problems occur when the underlying real assets fail to perform as expected. Or at worst don't exist at all.

There is no upside to holding Terra. If the system works, it'll always be grounded to 1 dollar. Luna on the other hand can go to the moon.

The names are the cleverest part of the whole scheme.

More accurately why would you want either when the whole thing is propped up by marketing hype.

To properly answer your question, Terra has no upside: no way to 10x. So yes, gambling.

Terra does not move in value. It’s like owning cash vs owning stocks.

The cash is less risky but it’s value does not change (apart from inflation).

Stocks are more risky but may give you profit over time.

>So why would one want to have Luna when you got Terra?

There are 3 different things: Governance related, market module related, and staking related.

You can spend 50 LUNA to submit a governance proposal. The second is to stake your LUNA. When your LUNA is staked the first benefit is that you can vote on governance proposals. Proposals can be onchain changes such as modifying a parameter or an offchain change which people should respect even if there is nothing technically forcing them to follow it.

There is a limited amount of UST that exists so what happens if more people want UST? You can burn LUNA to mint new UST. In times where the demand for UST is strong enough to make UST go above $1 it may be profitable for someone to burn their LUNA to mint UST.

Every transaction has gas fees. Any swaps between stable coins have a tobin tax. Using the market module to exchange UST for LUNA has a spread fee. All of these fees are collected and then distributed to the stakers. To help protect against times when the protocol is less active the fees are actually spread out over time. Right now every 5 blocks 5/9400000 of the reward pool is paid out to people staking. 9400000 is how many blocks there are in 2 years.