I am a little confused to answer your question, because you want to earn money without investing money. Actually you have done one way correctly, that is by mining. Well, I think there really isn't anything that is obtained for free without sacrifice. There might be another way to get free coins, that is by participating in bounties and airdrops. Thanks.

There's no free in this world buddy, if you want to earn you gotta invest something like money otherwise you won't get anything in return, if there is a way to earn without investing everyone would go for it.

you would want masternode if you want to earn without that much effort, while your holding your coins you also get more coins by holding possible more profit in the long run if you sell at higher price. 

you can't have everything at the same time! you don't want to spend anything, you don't want to mine anything, and you don't want to work. but at the same time you want to earn, you want to mine and you want to protect against 51% attack?!!!

that is not possible.
you have to give something to receive something in return.
for example you have to spend your computing power and mine some coin to contribute to its hashing power and make 51% attacks harder.
or you have to invest your money and buy some altcoin to have a share of it to run a PoS node and earn stakes.

you can run a full node of some coin, like bitcoin full node and contribute to its network and increase the decentralization of it a small amount but you won't be earning anything.

I'm pretty sure your example there is exactly what mining is, just with the added functionality of actually "handling" new transactions.

Нет, в Ёте нет пассивного дохода. Никакого.
И кошелёк Тринити не поддерживает сеть, т.к. сам не запускает ноду.