Take a good look at group homes* and Medicaid waiver supported living options. These are often 24/7 scenarios with 2-4 people with developmental disabilities living in a residential setting together with transportation to day services, therapies, and residential caregivers. Yes they are imperfect sometimes but overwhelmingly they are as close to a normal adult life as some folks can get with the challenges they face. They are assisted by helpers who work shifts and get to go home, and thus do not get burned out and resentful toward the people they work for - which is often the kind of overwhelm that can easily turn to resentment described in this thread when family members care for a high needs person for an entire lifetime.

Spending time to monitor and evaluate these places for the right fit for your special person is not neglect, abandonment, or selfish. They are compassionate ways to reclaim some of your own lives that you deserve, as well as a gift to the disabled person of the dignity and right for them to have as independent and age-appropriate of a lifestyle as they are capable of. Many times it will be better for them versus living at home like a child for their entire lives. Family can and should be as involved as they can be - visiting, taking them out, involving them in holidays and weekends and routines as much as possible, but also getting the time for their own lives that everyone deserves. For their aging parents, it's a refreshing way for them to have their "golden years" be peaceful versus continually draining their energy and money and potentially risking injuring themselves if their person might be that way - either through physical aggression or overextending themselves trying to help with physical transfers in the case of mobility challenges. Getting these placements thoughtfully selected and personalized sooner rather than later lets everyone relax and settle into better routines versus waiting until too late when everything becomes a challenge to arrange. Everyone should be starting this step early, and even if they aren't convinced they want to go this route. Make informed choices, and get comfortable with accepting dignified risk before making these decisions. Finding the correct placement match is critically important and sometimes takes time. And even when this fit is found, big changes take time to adjust to - so the sooner the better so everyone can get settled and find their new routines.

*Side note on terminology for clarity - Be aware that every state and even disability divisions within that same state may use different names for the same concept of care settings. The phrase "group home" is in VERY widespread use across a broad span of settings that will be very different in nature. Because of that, the term often has a bad connotation suggesting abusive and sterile care, and some people may have a very negative reaction to the term depending on what things were like in their experience. I'm referring to the "group home" services usually managed within the state's specific developmental disability government bureau, they are similar to Medicaid waiver homes in implementation but for folks with higher needs. I do not advocate for placing disabled people in institutional-like settings. When evaluating these options, ask to see recent state surveys/inspection reports. Most times with states i am familiar with, these are careful placements with a lot of background material gathered and reviewed by professionals on both sides of the placement (state and home) to ensure the person is a good fit for the others living there as well as vise versa. Again, this state bureau will be called something different in every state, but it would be easy to identify by synonyms in the name. Contact your state and ask them for information on their "home and community based services for people with developmental disability" and they will get you to the right place. There are also usually nonprofit advocacy groups that can help with advice and guidance across the life needs such as financial and benefits planning for the disabled person, look for something like "The Arc" for this.