Moggie is a blackthroat instead of a sav, but I've had her since she was little, and now she's adult. I love her, but having kept her so long, I do understand how folks get in over their heads buying a lizard that will get so large.
They aren't cheap to feed properly, and of course having/buying/building a proper sized enclosure, all the cleaning, the discovering that they generally are not 'puppys in scales' in behavior, it all tends to add up to the lizard just ending up neglected, given away or dead. The large monitors are not for the hesitant! If you wonder if you can/should keep a adult one, then you probably should not.

I'll state, I was advised Most Strongly NOT to get a blackthroat. I was told when I got her anyway, that I would be contacting them within a week saying "Come get this thing!" and although I cannot say that I've NEVER regretted getting Moggie, I certainly am glad that I DID get her. She's a wonder and a joy! And she is NOT a "pet" and not a puppy-dog tame lizard! She's a typical grumpy monitor! You just have to be a special person to appreciate monitor lizards that can eat your face!