Bitcoin fees get high when more people are trying to use the network than the available block space can handle. Miners prioritize transactions offering higher fees, so users bid against each other, especially during market spikes. The fee depends mainly on transaction size in bytes and network congestion, not the dollar amount sent. Sending from a SegWit or Taproot address, choosing a slower fee setting, or using the Lightning Network can reduce cost. Also check whether the wallet is showing a network fee plus its own service fee.