How can I convince the person to buy some XRP?.
If you're trying to really convince someone to buy XRP, then you need to point them in the direction of research that has supported you, encouraging them to invest in it. If you tell some people to go and do their own research, they can end up not doing it because maybe other activities of the day are taking away their attention, but if you do the research for them, sit them down, and show them these results, they may become convinced on the spot based on the data that you've shown them, which points out that it will be a good investment to buy XRP. If they remain unconvinced, don't force them.