That is not a good idea at all. For example: the new HTTP/3 over QUIC runs on top of UDP. There's a good chance most modern websites you use regularly use UDP, and most games and other real-time programs rely solely on UDP.
UDP is unreliable because the raw transport mechanisms on the internet are unreliable. TCP helps control the transport of these packets, but if you need more speed or want to implement it in a better way, then UDP is necessary.
UDP is unreliable because the raw transport mechanisms on the internet are unreliable. TCP helps control the transport of these packets, but if you need more speed or want to implement it in a better way, then UDP is necessary.