Whoever said that to you either doesn't know what they're talking about or just doesn't want the best for you.  You really gotta think this through logically. how can your coins actually be safe long-term if you aint fully in control of the wallet itself? Binance and KuCoin are exchanges, they ain't wallets.  So what happens to all your coins if one day they just up and stop working? I mean, didn't you hear about what went down with one of the biggest exchanges last year? It was nuts.  

Anyway bottom line is, if you care about keeping your coins truly secure for the long haul, you gotta control the private keys to your wallet.  Exchanges can go belly up anytime.  Don't take unnecessary risks here.  Do your research and get yourself a proper crypto wallet that you control. As for Trust Wallet, I don't personally use it so I can't recommend it. It's probably good enough for smaller amounts.  But if you plan to keep your coins long term, I wouldn't use a hot wallet for that.