This handy tool converts from points from bloated ASCII to binary LAS or compressed LAZ file. When you send us a support request for this tool please include a few lines (around 20 to 50) of your ASCII text representation as well the command lines (aka parse strings) that you have already tried:
txt2las -i ascii.txt -parse sxyzsit -o lidar.laz
Also see the many answer and question discussion threads in the LAStools user forum. This tool is 100% open source LGPL. For more details see the README file.