If I rip all my CD's to flac files do I still need a CD transport?

If asked my answer would be “Yes- you should always have a transport/player as a fallback”. I don’t know how many discs I own but a large majority of them (what I listen to most often) are ripped as .WAV files onto a playback server. When I buy a new CD it gets ripped and then stored away (99% of the time). The other 1% of the time is when I use a transport to listen to the music prior to deciding which discs to rip. An example being when you purchase a large box set. Two weeks ago I purchased two sets which combined contained close to 90 discs. This is a case where I want to listen to each disc first prior to deciding which to rip.

I stream a lot of music as well- helps me decide what to purchase on disc beforehand. But if internet service goes down a streamer is worthless. The server will still work via Wi-Fi but if it has an issue I can always play the disc. CD’s are cheap and compared to what you make selling them their not really worth getting rid of (unless space/clutter is the issue). 
Keep your player and your discs!

What happens when your hard drive chashes?  If you have the Cds, you can still recover the music. Do you have a storage space problem. I put my CDs on hard drives, but I still keep the media - just in case.

What happens when your hard drive chashes?

That's what backups and restores are for.   ITs' important to not overlook that because eventually every hard drive will fail.  Keeping the CDs is another safeguard but ripping thousands a second time is not a desired use of time.  So unless you want to be forced to go back to a CD player at some point,   have that backup and restore solution in place.  OR at that point punt and go mostly with streaming from services like qobuz, etc.

Simple...

I had 2 hard drive of 5GB  ... One conected all the time...

The other is a safe...

What happens when your hard drive chashes?  If you have the Cds, you can still recover the music.

I have 3 copies of my music library, one master and then two backups. It is super simple and cheap to backup a music library. In fact it is orders of magnitude easier than saving CDs and then potentially re-ripping the audio files.

Yes all HDs fail eventually. One thing that helps a lot is to NOT keep your music library files on your boot drive. If your library HD is on a separate disk (or NAS  drive etc) it is MUCH less likely to crash and burn. That outcome almost always goes to the boot drive.