people with one child

Alice
Hello there. I have a hand full toddler and since he was born I couldn't picture myself having a second baby. 
Parents with one child, do you regret not having a second baby? Or is it not as bad? 
I feel like with one child I can afford to give him a good life, school, clothes, trips, and all that. With two it will be a bit tight. Mentally and emotionally I don't know if I can handle second baby. But I don't want to regret it. 
Also, why do people keep telling me (no you have to have another baby, it's not good, you have to) why is that? What's so bad about having just one. I give all the attention and love and support to my baby so he doesn't feel lonely or sad.