Sometimes new coins get big pump with multiple times, making huge profits for investors.
Sure new coins almost all the does that at the time of being listed newly and very many times, they still come down crashing before some stability if they are real. Those are the times to offload and buy in again.
You are right on new coins pumping when newly listed but it occurs most often in the era of bullish runs it rarely happens now instead the coin becomes worthless immediately after listing, although you can rule out some few of them that get pumps in some occasions due to fundamentals or other reasons.
Back to OP assumption that cryptocurrencies transaction is well secured yes of course at some extent but its well confirmed that cryptos transaction is irreversible hence you have to be extraordinarily careful in your dealings.