It does seem pretty daunting in retrospect. In the earlier 17th c., the odds of surviving your "seasoning" were sometimes 3 out of 4. In Virginia most children lost at least one parent before they were adults; more than a third lost both. A couple would marry, have a child, the mother would die, the father would remarry and have another child, he would die, his widow would remarry...and his first child ( and her inheritance) would be under the authority of two people not related to her. A household could be an uncle, his niece, and his recently widowed sister. It must have had an awful effect on people's mental health

The answer as to why they came anyway? England had a growing population and an old agricultural economy, where all the land was taken. If you were a young woman in Shropshire circa 1660, daughter of a tenant farmer, your options could be few . The typical village would be quite aware of all the possible combinations- whether a weaver needed an extra pair of hands and had a marriageable son, whether the recent draining of a water meadow had enabled a tenant farmer to increase his herd to the point where he needed a cowboy ( yes, that was the name of someone who watched the cattle). After all the calculations, there would often be extra young people who really didn't have a place. Those extra people heard news of a boom in tobacco , in early years on the Chesapeake, and how fortunes were being made on land that was there for the taking, and they sometimes took their chances and left. That's why a great deal of the immigration into the Chesapeake until around 1680 was of indentured servants: people who were young, had little to lose, and much to gain. And, after the tobacco boom had passed, and the best land taken or exhausted ( tobacco is a hard on the soil) the news did get back to England that prospects were no longer as good, and that stream of indentured servants did slacken. So much that, after 1680, Virginia planters more and more bought enslaved labor from the Caribbean.

Bernard Bailyn: The Barbarous Years