Crypto is perfectly safe if you can keep all your secret information to yourself and for a long time.
Safety in my opinion is not only about your seed phrase or your private keys which you correctly called "secret information", safety should also be about double checking what you want to invest into, you may invest in a scam project that specializes in rug-pull scam for example, when you are scammed by such project, you will still have your tokens well protected in your wallet, but by then they have no worth or use, crypto safety is investing in the right project first of all, then safeguarding your coins.
does i invest full money in crypto?
It depends on where you invest.
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No matter where you invest, or in what you invest, do not invest 'all your full money into it".