Security concerns in not only in the cryptocurrency. It's even in banks or in the house also. I believe nothing is safe 100%. We can take some security measure which avoids many things. Like I never store my any fund in the exchange except I have to sell or buy at that moment. With time to time check your system not just for coins even for your data also is it secure or not phone or any device. It's good to use desktop or hardware wallet for the larger amount.