Some research suggests that monarchs raised in captivity lose their ability to migrate. The primary reference in this debate is "Contemporary loss of migration in monarch butterflies", a paper published by researchers at the University of Chicago's Department of Ecology and Evolution in 2019 (found here). For this study, researchers acquired both commercially bred adults and wild caught adults and raised their offspring in various conditions for two generations. To gauge the quality of each generation, they measured the ability of each generation to "orient" itself to face south with a flight simulation chamber, and measured some reproductive and morphological characteristics. Overall, they found that the offspring of commercial-bred butterflies lacked most characteristics of migratory butterflies when raised in any conditions. Those raised indoors, even with daylight conditions and weather corrects, often lacked migratory characteristics, but those raised outdoors were prepared to migrate. Their key conclusion in the article for citizen scientists is, "In terms of seasonal rearing by summer hobbyists and school groups, we would argue that the practice of raising monarchs in this setting is net positive, especially in the link it creates between people and their natural environment. The fact that so many school-age children raise monarchs is probably one of the reasons the insect is so popular and why the public directly participates in conservation efforts on behalf of the species. This practice should absolutely continue, with the added caveats that the butterflies should be locally sourced and then subsequently reared outdoors where they will be exposed to the full spectrum of natural environmental conditions, ensuring that reared monarchs will have the best chance of migrating successfully."
The key takeaway should be that commercially bred adult monarch butterflies will cause more harm than good to the general monarch butterfly, and should not be purchased. If you want to see monarch butterflies, plant milkweed and they will fly in over time.
Less than 10% of the monarch eggs survive in the natural habitat. So once you see the eggs on the milkweed you can protect them from the predators using a diy habitat. You can also get mosquito netting or a netting fabric and loosely tie around the milkweed. You can also purchase larger habitats that you can keep outdoors. These habitats are large enough that you can keep a whole Milkweed container/pot inside and not have to worry as much about keeping the caterpillars fed. Simply keep a eye on the milkweed, and once the leaves are all gone, swap the pot out and move the caterpillars to the new plant.
This is discouraged, but if you really must, you can also bring the eggs, caterpillars into a indoor habitat. Bringing them indoors involves keeping the habitat clean and adding milkweed as needed. You can buy habitats online preferably big enough to put 1 gallon milkweed plants and side zipper to swap plants in and out.
To raise the monarchs indoor, make sure your hands are washed and clean before you touch the caterpillars or the milkweed.
What’s involved: Providing the enclosure with proper light and air exposure. Providing humidity ( a moist paper towel, clean and fresh milkweed. Cleaning the enclosure twice a day -picking up soiled paper towel(s) and replacing milkweed with clean/washed milkweed. You can use water bottles to keep the milkweed fresh. You can also create your own stands just drill holes in a cardboard box and stick the floral tubes in the box.
What’s important: The most important thing to do is keep their enclosure and food clean and not overcrowd the caterpillars. Infectious diseases of all kinds are more easily spread in crowded conditions where bodily fluids (including frass, their scat) is located.