IIRC Williams went on to sink as much of TSR's money as possible into buying up the rights for the Buck Rogers RPG ... which flopped and sunk without a trace, crippling TSR's finances.
TSR's finances were in perpetual disarray from about '83 forward... when the D&D bubble popped.* TSR had built itself around the assumption that growth would occur at the same rate as it had during the bubble, and was screwed when it didn't. It never fully recovered. Even though Williams' mismanagement didn't help, by the mid 80's significant percentage of gamers had moved onto computer gaming and their purchases of hardcopy games dropped precipitously. They stumbled on long enough to be around when WOTC came into bucketloads of cash, but they were anything but a healthy company.
Not to mention the Buck Rodgers RPG is far from only "flopped and sunk without a trace", whether from TSR or elsewhere in the industry. (Even games that were huge successes (by the standards of the day) are by-and-large completely forgotten today.) At the height of the bubble ('82-'83) it seemed a new RPG was coming out every week, and the premises of the games were increasingly specialized and/or outlandish. By 1983, the market for tulip bulbs was beyond saturated**. By 1984 it was busted. By 1993, when the Buck Rodgers RPG was released, it would have taken a miracle for any RPG to be a breakout hit.
*The largest problems that hardcopy gaming (board, pen-and-paper, etc...) companies face are the replayability factor and the scaling factor. For the first, you can buy a set of rulebooks and literally play for years without further purchase. For the second, one guy can purchase a set and then ten or more others can play using that set for years. Once a significant proportion of your userbase has a set of your products, you're screwed. There's a reason why every gaming company of the era got into supplements and expansions and ancillary products and media as fast and deep as possible - it's the only way to survive. WOTC didn't create the idea of endless supplements and expansions (as many seem to think), they merely perfected the implementation by convincing players they were vital to continued gameplay rather than being optional.
** I remember a meeting of our gaming group in 1983 where we were deciding which GM/game would be added to our rotation to replace one that was moving away... we literally had twenty or thirty different RPG's in hardcopy physically sitting on the table. When I attended Dracon I (or was it Hexacon I, can't remember as there were so many start-up gaming cons back in the day) in 1984 I took something like ten different games from my personal collection to the con. (Met Tracy Hickman there, out stumping the then newly released Dragonlance.)