I notice a handful of Devs do that, start a game and before they finished it, start a new game. Some go a whole year before hearing anything about any kind of update. I used to donate some money but now I just wait to see if a game gets finished or not.
It's why they do it. It's like going fishing and setting multiple lines. Then you fish the spot that's active.
The few dollars generated by the lesser games still are profitable, and they turn out content for the paying people.
On Steam, this behavior earns a game an automatic thumbs-down from me. But people are stupid enough to support Dr. Crackhead on Patreon to over $30,000/month while he makes them wait 5+ years between updates.
Most gamers probably shouldn't be allowed to handle their own money!