How can I trust a Bitcoin wallet like bitcoin.co.id to save my own money or Bitcoin or other digital currencies that I have?

There are many types of wallets, from secure to most secure. But in general, you should not trust hot wallets also known as web wallets or online wallets.

The most secure wallets are paper wallets, hardware wallets, Bitcoin core, or desktop wallets respectively.

Wallets that let’s you hold your private key’s are generally considered secured and trusted.

Wallets on Exchange forums or generally considered risky because of the potential DDOS attacks and it’s exposure.

But remember, that does not stop us from holding Bitcoin on Exchange forums. A huge number of Cryptocurrency users store their coins on Exchange wallets because it’s easy to move, trade, and hold multiple currencies.

If you are planning to hold a large number of coins then go for paper wallet or hardware wallet otherwise use Bitcoin core, Exodus.io, Coinbase etc.