I have 9 TB of storage. I'm not concerned with squeezing my 30,000 various SW sounds down to 15GB to help them fit on Google drive. I don't collect sounds for collecting's sake. I use them. FLAC's don't work natively in Final Cut Pro, Premiere, Audition, ProTools or most programs for that matter. There might be plugins that work, but that's extra hassle. WAVs work.

Not trying to sound like a jerk, but converting them to FLAC is a step that would have to be undone when I actually need to use them. I hope that makes sense.